Troubleshooting
Simple Fault Finding Procedure
The below guide is a quick and easy method to simply troubleshooting your Worcester Bosch Boiler, simply use the fault finding method below:
- Electrical Checks. Test the electrical circuits by checking for short circuits, continuity (earth) and resistance (to earth). Ensure system has appropriate electrical polarity.
- For Electrical 230V Supply. Inspect the boiler unit to ensure that the supply voltage is 230 V.
- For Gas Supply. Ensure the boiler has a gas supply. Check that it has been purged.
Warning Warning: Ensure only qualified CORGI registered contractors do these checks, it is illegal and danergous if you conduct your own gas checks!
- Heating system Filling. Check the boiler is full of water and pressurised to 1-1.5 BAR. Incorrectly filled boiler will reduce your efficiency.
- Control. Ensure main switch is set to ‘on’
- Temperature. ensure your heating temperature is set to the maximum setting.
- External Controls. Ensure that the controls circuit thermostat is calling for heat.
Worcester Bosch Boiler F7 Error Code
24i RSF Fault Finding
Follow the troubleshooting chart below to trace your 24i RSF issue and identify your boiler’s diagnosis. You will then be able to find the a suitable replacement part and fix your boiler.
Circuit Diagram
General Faults
PCB Faults
Thermostats, Pump and Fan Faults
Thermistor, Hardness Continuity and Short Faults
Ignition Faults
Air Pressure Switch and Gas Valve Faults
Modulating Valve and Flow Switch Faults
Worcester Bosch Bi and SBi Troubleshooting
Conduct the following tests below to help fault find the specific issue you are experiencing with your Worcester Bi and SBi Boiler models. You can check the system for demand, indication or conduct a system test.
Facia Indicator Test
Boiler Demand Test
System Test
Worcester Bosch CBi
Use the troubleshooting table or fault finding flowcharts below to identify your Worcester CBi fault and troubleshoot either a solution or replacement part.
CBI Fault Lights
CBi Fault Finding Chart
Worcester Bosch CDi
The Worcester Bosch fault finding table below will help you diagnose your boiler’s fault and help you take the next decision in fixing the issue. You may want to then buy a replacement part of get a service engineer in to fix the issue.
CDi Troubleshooting Table
Play Code | Description | Remedy |
---|---|---|
A1 | Pump has run dry. | Check system pressure, add water and bleed system as necessary. |
A7 | Hot water NTC Sensor defective. | Check hot water NTC sensor and connecting lead for circuit breaks/short circuits. |
b1 | Code plug not deteched | Insert code plug correctly, test and replace if necessary. |
C6 | Fan speed too low. | Check fan lead and connector, and fan; replace as necessary. |
E2 | CH flow NTC Sensor defective. | Check CH flow NTC sensor and connecting lead. |
E9 | Safety temp. limiter in CH flow has tripped. | Check system pressure,check safety temp. limiters, check pump operation, check fuse on pob, bleed appliance. |
EA | Flame not detected. | Is gas cook turned on? Check gas supply pressure, power supply, iginiter electrode and lead, ionisation sensing electrode and lead, flue duct and CO2 level. |
F0 | Internal error | Check electrial connector contacts, programmer interface modeule ignition leads are not loose; replace pcb if necessary. |
F7 | Flame detected even through appliance switched off. | Check electrode assembly, dry pcb. Flue clear? |
FA | Flame detected after gas shut off. | Check gas valve and wiring to gas valve. Clean condensation trap and check electrode assembly. Flue clear? |
Fd | Reset button pressed by mistake. | Press reset button again. |
CDi Central Heating Function
CDi Preheat and DHW Function
Worcester Bosch Highflow 440
Use the Fault Finding table below to diagnose your Worcester Highflow 440 problem to allow you to get your boiler working again.
Highflow 440 Troubleshooting Table
Display code | Fault Description | Check repair / replace as necessary |
---|---|---|
F0 | Internal error | Transformer. |
All connections to control board. | ||
Otherwise replace control board. | ||
F7 | Flame detected with no demand | Gas valve |
Flame sense electrodes/cables | ||
Moisture on control board. | ||
Blocked condonsate trap. | ||
Otherwise replace control board. | ||
FA | Flame detected with after gas | Cables and connections to gas valve. |
Gas valve switched off | Condonsate trap. | |
Flue (for blockages). | ||
Otherwise replace control board. | ||
Fd | Reset button pressed by mistake | Press reset button again. |
P1,P2,P3,P1 | Please wait , initialisation in progress | Replace fuae S12. |
Otherwise replace control board. | ||
No central heating hot water OK | Demand signal from roomset/CH timer (r link fitted at ST4) | |
CH channel of facia mounted programmar (if fitted). | ||
CH control knob position. | ||
No hot water, central heating OK | Flow turbine | |
Demand signal from DHW timer (for link fitted at ST 8). | ||
DHW channel of facia mounted programmer (if fitted). | ||
No functions | 230V fuse (S11). | |
Transformer. | ||
Otherwise replace control board. | ||
Poor performance / noises | Fan/fan harness. | |
Sensors not fixed or out of specification. | ||
Gas pressure / blockage. | ||
Water pressure / blockage. | ||
CO2 mix. | ||
Flue blockage. | ||
Noisy ignition | Spark electrodes / cables. | |
Gas valve. | ||
Gas supply. | ||
CO2 mix. | ||
Seals. | ||
A5 | Tank sensor fault | Tank sensor (8000-20000 ohms at room temperature). |
Wiring and connections to sensor. | ||
A7 | DHW sensor fault | DHW sensor (8000-20000 ohms at room temperature). |
Wiring and connections to sensor. | ||
A8 | Module fault | Night set black module TR212E and / or Roomstat TR2. |
Wiring and connections between modules. | ||
b1 | Code plug not detected | Code plug version , condition and fitting. |
If OK replace control board. | ||
C1 | Fan speed too low | Fan harness and connections. |
Fan. | ||
Otherwise replace control board. | ||
d3 | Terminals 8-9 not shorted at connector ST7 | Safety overheat thermostat for underfloor heating system (if fitted). |
Otherwise fit link. | ||
d5 | Condensate pump failed | Mains supply to condensate pump. |
Condensate Pump unit. | ||
Continuity of all cables to pump unit. | ||
d6 | Tank overheat | Tank sensor is correctly fixed to tank. |
Wiring and connections to sensor. | ||
E2 | CH flow sensor fault | CH flow sensor (8000-20000 ohms at room temperature). |
Wiring and connections to sensor. | ||
E9 | Safety overheat device tripped | All air vented. |
Water pressure above minimum. | ||
Leaks or blockage. | ||
Condition and attachment of CH flow sensor. | ||
Pump and associated wiring /connections. | ||
Connections and wiring to overheat thermostat devices. | ||
Otherwise replace control board. | ||
EA | Flame not detected | Gas present and at correct pressure. |
Combustion CO2 level. | ||
Condition of flue. | ||
Ignition electrodes. | ||
Ignition harness and connections. | ||
Flame sense harness. | ||
Flame sense cables and connections . | ||
Gas valve. | ||
Otherwise replace control board. |
Worcester Bosch Heatslave
The Worcester Heatslave troubleshooting tables below will aid you in diagnosing the problem with your boiler. This will allow you to call in a service engineer and purchase the exact replacement parts your need to fix the problem.
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Worcester Heatslave Fault Finding Table
PROBLEM | CAUSE | REMEDY |
---|---|---|
LOCKOUT : | ||
Pulsation on start | CF-Flue draught incorrect | CF-Check flue draught |
Combustion settings incorrect | Set up as in installation instructions | |
Faulty nozzle | Replace nozzle | |
Intermittent lockout | Bad electrical connection | Check control box/electrical connections |
Intermittent flame detection fault | See flame detection fault | |
Down draught | Extend flue or fit an anti-downdraught cowl (CF only) | |
Burner motor fails to operate | Faulty motor electrical supply to motor | Check for 230v at motor plug during startup period |
Control box fault | Replace control box | |
Flame detection fault | Photocell filmed over (dirty) | Clean |
Photocell faulty | Replace | |
Control box faulty | Replace | |
Air adjustment fault | Incorrect CO2 | Set up as in installation instructions |
No oil from nozzle | No oil at pump | Check and refill oil tank/bleed oil line |
Check and clean filters & valves from oil tank to boiler | ||
Air in pump | Bleed pump | |
Nozzle blocked | Replace nozzle | |
Faulty pump or drive | Replace | |
Faulty mechanical shut off valve | Clean or replace | |
Ignition failure | Electrode settings incorrect | Set up as in installation instructions |
Faulty ignition transformer | Replace | |
Open circuit ignition | Check and replace electrodes or high tension leads if necessary | |
Faulty control box or electrical connections not properly made | Correct electrical control box connections or replace control box | |
BURNER FAILS TO START | No power to boiler | Check electrical / control circuit |
Faulty boiler thermostat | Check by temporarily linking out high limit and control thermostat | |
Programmer open circuit | Check by temporarily linking 8 & 9 on the connector | |
Faulty control box | Replace | |
HIGH SMOKE NUMBER | Air intake /flue blocked | Check & clear air intake/flue |
Incorrect combustion settings | Set up as in installation instructions | |
Oil pressure incorrect | Adjust to correct pressure | |
Incorrect components used on combusion head | Check with installation instructions | |
Faulty nozzle | Replace nozzle | |
FAULTY BOLIER OPERATION : | ||
Noisy operation | Pump noise from air in pump or worn pump | Bleed air from pump or replace pump |
Wom motor bearings | Replace motor | |
Fan out of balance | Replace fan | |
Boiling | Faulty boiler thermostat | Replace if necessary |
Short circuit boiler thermostat | Takeout of circuit to check | |
Thermostat bulb not fully home in pocket | Ensure bulb is pushed fully home | |
No primary water circulation | Check system/circulating pump | |
Short Cycling | Burner rating incorrect | Correct burner rating |
Boiler thermostat differential incorrect | Replace boiler thermostat | |
External controls not operating correctly | Check and correct external controls | |
OIL SMELLS | Blocked flue, furnes on startup | CF-Check flue with gauge and seals/gaskets |
RS-Check seals/gaskets | ||
Oil soaked boiler, faulty burner operation, numerous lockouts | Rectify burner operation and lockouts | |
Odour in boiler room, oil leaks from pipework, flexible hoses connections | Rectify oil leaks, replace components if necessary |
Worcester Bosch Greenstar HE
If you have a problem with your Greenstar HE series boiler use the troubleshooting table below to identify the problem.
Worcester Greenstar HE Troubleshooting Table
Display Code | Description | Remedy |
---|---|---|
A7 | Hot water NTC sensor defective | Check hot water NTC sensor and connecting lead for circuit breaks/short circuits. |
A8 | Break in communication | Check connecting lead to programmer |
AC | Module not detected. | Check connecting lead between TA211E/TR212E and Heatronic |
b1 | Code plug not detected. | Insert code plug correctly, test and replace if necessary. |
C1 | Fan speed too low. | Check fan lead and connector, and fan; replace as necessary. |
d3 | Jumper 8-9 not detected. | Connector not connected, link missing, underfloor heating limiter tripped. |
E2 | CH flow NTC sensor defective | Check Ch flow NTC sensor and connecting lead. |
E9 | Safety temp. limiter in CH flow has tripped. | Check system pressure, check safety temp. limiters, check pump operations, check fuse on pcb, bleed appliance. |
EA | Flame not detected. | Is gas cock turned on? Check gas supply pressure, power supply, igniter electrode and lead, ionisation sensing electrode and lead, flue duct and CO2 level. |
F0 | Internal error. | Check electrical connector contacts, programmer interface module iginition leads are not loose; replace pcb if necessary. |
F7 | Flame detected even though appliance switched off. | Check electrode assembly, dry pcb. Flue clear? |
FA | Flame detected after gas shut off. | Check gas valve and wiring to gas valve. Clean condensation trap and check electrode assembly.Flue clear? |
Fd | Reset button pressed by mistake. | Press reset button again |
P1,P2,P3,P1 | Please wait, initalisation in progress | 24 V fuse blown. Replace fuse. |
Worcester Bosch Greenstar Utility
Check out the Worcester Greenstar Utility fault finding tables below to diagnose your boiler’s issue. Follow the table from top to bottom to help you identify the issue then you can find the corresponding replacement part.
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Worcester Greenstar Utility Fault Finding Table
PROBLEM | CAUSE | REMEDY |
---|---|---|
FAULTY BOLIER OPERATION : | ||
Noisy operation | Pump noise from air in pump or worn pump | Bleed air from pump or replace pump |
Wom motor bearings | Replace motor | |
Fan out of balance | Replace fan | |
Boiling | Faulty boiler thermostat | Replace if necessary |
Short circuit boiler thermostat | Takeout of circuit to check | |
Thermostat bulb not fully home in pocket | Ensure bulb is pushed fully home | |
No primary water circulation | Check system/circulating pump | |
Short Cycling | Burner rating incorrect | Correct burner rating |
Boiler thermostat differential incorrect | Replace boiler thermostat | |
External controls not operating correctly | Check and correct external controls | |
OIL SMELLS | Blocked flue, furnes on startup | CF-Check flue with gauge and seals/gaskets |
RS-Check seals/gaskets | ||
Oil soaked boiler, faulty burner operation, numerous lockouts | Rectify burner operation and lockouts | |
Odour in boiler room, oil leaks from pipework, flexible hoses connections | Rectify oil leaks, replace components if necessary |
Worcester Bosch Danesmoor Regular, Utility, System, WM and FS
The Worcester Danesmoor series of boilers covers a wide range of quality boilers offered by the company. To fault find any issues with this range follow our fault finding chart or troubleshooting tables below.
Troubleshooting Table
PROBLEM | CAUSE | REMEDY |
---|---|---|
LOCKOUT: | ||
Pulsation on start | CF - Flue draught incorrect | CF - Check flue draught |
Combustion settings incorrect | Set up as in installation instructions | |
Faulty nozzle | Replace nozzle | |
Intermittent lockout | Bad electrical connection | Check Control box/electrical connections |
Intermittent flame detection fault | See flame detection Fault | |
Downdraught | Extent flue or fit a downdraught cowl | |
Burner motor fails to operate | Faulty motor or electrical supply to motor | Check for 230v at motor plug during startup period |
Control box fault | Replace control box | |
Flame detection fault | Photocell filmed over (dirty) | Clean |
Photocell faulty | Repalce | |
Control box fault | Repalce | |
Air adjustment fault | incorrect CO2 | Set up as in installation instructions |
No oil from nozzle | No oil at pump | Check and refill oil tan |
Check and clean filters & valves from oil tank to boiler | ||
Air in pump | Bleed pump | |
Nozzle blocked | Replace nozzle | |
Faulty pump or drive | Repalce | |
Faulty mechanical shut off valve | Clean or replace | |
Ignition failure | Electrode settings incorrect | Set up as in installation instructions |
Faulty ignition transformer | Replace | |
Open circuit ignition | Check and repalce electrodes or high tension leads if necessary | |
Faulty control box or electrical connections not properly made | Correct electrical control box connections or replace control box | |
BURNER FAILS TO START | No power to boiler | Check electrical / control circuit |
Faulty boiler thermostat | Check by temporarily linking out high limit and control thermostats | |
Programmer open circuit | Check by linking 8 & 9 on the connector | |
Faulty control box | Replace | |
HIGH SMOKE NUMBER | Air/flue intake blocked | Check & clear air/flue intake |
Incorrect combustion settings | Set up as in installation instructions | |
Oil pressure incorrect | Adjust to correct pressure | |
Incorrect components used on combustion head | Check with installation instructions | |
Faulty nozzle | Replace nozzle | |
FAULTY BOILER OPERATION: | ||
Noise operation | Pump noise from air in pump or wom pump | Bleed air from pump or replace pump |
Worn motor bearings | Replace motor | |
Fan out of balance | Repalce fan | |
Boiling | Faulty boiler thermostat | Replace if neccesary |
Short circuit boiler thermostat | Take out of circuit to check | |
Thermostat bulb not fully home in pocket | Ensure bulb is pushed fully home | |
No primary water circulation | Check System / circulating pump | |
Short Cycling | Burner rating incorrect | Correct burner rating |
Boiler thermostat differential incorrect | Replace boiler thermostat | |
External controls not operating correctly | Check and correct external controls |
Fault Finding Chart
BOSCH WORCESTER CONDENSING BOILER FAULT CODES |
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f your Bosch Worcester condensing boiler is showing a fault code it should be listed below, in some cases these can be fixed by the competent DIY'er
A1 | PUMP HAS RUN DRY Check system pressure, add water and then bleed if necessary. |
A7 | HOT WATER NTC SENSOR DEFECTIVE Check NTC sensor and connecting leads for circuit breaks and/or short circuits. |
A8 | BREAK IN COMMUNICATION Check connecting lead to programmer |
b1 | KEYED PLUG NOT DETECTED Insert keyed plug correctly, test and replace if necessary. |
C1 | FAN SPEED TOO LOW Check fan lead and connector, and fan; replace as necessary. |
d3 | JUMPER 8-9 NOT CONNECTED Connector not connected, link missing, or under floor heating limiter tripped. |
E2 | CH FLOW NTC SENSOR DEFECTIVE. Check CH flow NTC sensor and connecting lead. |
E9 | SAFETY TEMPERATURE LIMITER IN CH FLOW HAS TRIPPED Check system pressure, check safety temp. limiters, check pump operation, check fuse on pcb, bleed appliance. |
EA | FLAME NOT DETECTED Is gas cock turned on? Check gas supply pressure, power supply, igniter electrode and lead, ionisation sensing electrode and lead, flue duct and CO2 level. |
F0 | INTERNAL ERROR Check electrical connector contacts, programmer interface module ignition leads and bus module are not loose; replace pcb or bus module if necessary. |
F7 | FLAME DETECTED ALTHOUGH APPLIANCE IS SWITCHED OFF Check electrode assembly, dry pcb. Flue clear? |
FA | FLAME DETECTED AFTER GAS SHUT OFF Check gas valve and wiring to gas valve. Clean condensation trap and check electrode assembly. Flue clear? |
Fd | RESET BUTTON PRESSED BY MISTAKE Press reset button again! |
P1,P2,P3 | PLEASE WAIT INITIALISATION IN PROGRESS 24 Volt fuse blown, replace fuse! |
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Worcester Bosch CDI Classic Combi Boiler Error Codes
Fault Description | System Behaviour |
---|---|
A1 | Water is leaking or the pump needs replacing or freeing due to the pump running dry. |
A7 | The hot water negative thermistor coefficient (NTC) sensor is defective – the hot water sensor or connecting leads need checking. |
A8 | Break communication to FX sensor controls electrical connections need checking. |
B1 | Code plug not detected . |
C6 | Fan speed too low – the fan lead and connector need checking and may need replacing. |
E2 | Central heating (CH) water flow negative thermistor coefficient (NTC) sensor defective check CH flow NTC sensor and connection leads. |
E9 | Safety temperature limiter in central heating (CH) flow has tripped the system pressure or safety temperature limiter needs checking |
EA | Flame not detected due to a gas issue – the gas supply, power supply or igniter, electrode and lead need checking – contact a Gas Safe installer. |
F0 | Internal error – electrical connector contacts or programmer interface module – check ignition leads are not loose. |
F7 | Flame detected even though the appliance is switched off – check the electrode assembly is dry and the pcb and flue are clear. |
FA | Flame detected after gas shut off – the gas valve needs checking – hire a Gas Safe installer. |
FD | Reset button pressed by mistake – press reset button again. |
Worcester Bosch CDI Highflow Combi Boiler Error Codes
Fault Description | System Behaviour |
---|---|
A1 | Pump dry run detection or pump is running in air the system pressure needs checking |
A5 | Tank negative thermistor coefficient (NTC) defect |
A7 | Domestic hot water (DHW) negative thermistor coefficient (NTC) defect |
A8 | Energy Management System (EMS) communication error |
B1 | Code plug not detected |
B2, B3, B4, B5, B6 | Data error |
B7 | Burner control error |
C6 | Fan defect |
D3 | External temperature limiter |
D5 | Condensate pump failure |
D6 | Internal heat bank overflow |
EA | Flame not detected |
E2 | Primary negative thermistor coefficient (NTC) defect |
E9 | Safety temperature limiter in central heating (CH) flow stat tripped |
F0 | Internal error |
F1 | ROM fault |
F7 | Flame detected after appliance has been shut off |
FA | Flame detected after gas shut off |
FD | Reset button pressed – try pressing the reset button again |
Worcester Bosch CDi Compact / Greenstar 25/30 Si Combi / Greenstar 27/30 I system Boiler Error Codes
Fault Description | System Behaviour |
---|---|
T1 | Ignition test – checking the igniter spark |
T2 | Fan test – checking the basic fan |
T3 | Pump test – checking the basic pump |
T4 | Three way valve test |
T6 | Ionisation oscillator test |
9A 362 | error – incorrect HCM fitted |
9U 233 | Heat Control Module (HCM) error – problem with code plug |
B7 257 | Internal error – possible control board problem |
C6 215 | Fan problem – fan running too fast |
C7 214 | Fan problem – fan not running |
D1 240 | Return sensor error – sensor may be wet or damaged |
E2 222 | Flow sensor short circuit error |
E5 218 | Flow temperature too high |
E9 219 | Safety sensor fault – temperature too high, sensor short circuit or open circuit |
EA 227 | No flame detected or flame signal loss during operation |
F0 237 | Internal error |
F7 228 | Flame error – false flame or flame detected before burner started |
FA 306 | False flame fault – flame detected after burner stop |
FD 231 | Mains power fault – electrical power interruption |
FA 364 | Gas valve EV2 leak test failed – gas valve leak |
FB 365 | Gas valve EV1 leak test failed |
A1 281 | Pump stuck or running with air in the system |
C1 264 | Airflow stopped during operation |
C4 273 | Airflow present during last 24 hour |
D1 240 | Return sensor short circuit |
D4 271 | Temperature difference between flow and safety sensor exceeds limit |
E9 224 | Max thermostat activated – flue gas thermostat overheat |
EA 227 | No ionisation detected after ignition |
EF 349 | Central heating boil detected – boiler operating at minimum burner load with temperature difference greater than 18°C between Flow & Return. |
NO CODE 212 | Safety or flow temperature rising too fast |
Worcester Bosch CDi Classic Regular Boiler Error Codes
Fault Description | System Behaviour |
---|---|
B1 | Code plug not detected |
C6 | Fan speed too low |
E2 | Central heating (CH) flow negative thermistor coefficient (NTC) sensor defective |
E9 | Safety temperature limiter in central heating (CH) flow has tripped |
EA | Flame not detected |
F0 | Internal error |
F7 | Flame detected even though appliance switched off |
FA | Flame detected after gas shut off |
FD | Reset button pressed by mistake |
Worcester Bosch Greenstar I System / Combi Boiler Error Codes
Fault Description | System Behaviour |
---|---|
226 | Service tool has been connected in the blocking error history menu |
FD 231 | The power has been interrupted during a lockout |
C7 214 | Fan does not run during the start up phase – fan harness connector needs checking |
C6 215 | Fan speed too high – check the fan harness and connector |
C7 216 | Fan speed too low – check the fan harness and connector |
C7 217 | Fan has stopped during appliance operation |
C1 264 | Fan stopped during operation |
C4 273 | Continuous fan operation for the last 24 hours – appliance temporarily blocked |
E2 222 | Flow temperature sensor shorted |
E2 233 | Flow temperature sensor disconnected |
E9 276 | Primary flow temperature exceeded 95°c |
E2 350 | Flow temperature sensor shorted |
E2 351 | Flow temperature sensor disconnected |
FA 306 | Ionisation detected after the gas valve closed |
EA 227 | No ionisation detected after ignition |
F7 228 | Isioniation current detected before burner start |
EA 229 | Loss of ionisation signal during operation |
EA 261 | Heat control module (HCM) potentially defective – reset the appliance |
9U 233 | Control box or heat control module (HCM) is defective or loose, the HCM needs to be checked |
C4 237 | Control box or heat control module (HCM) is defective |
F0 238 | Gas valve or control box error – gas valve coils need checking |
F0 239 | Control box or the heat control module (HCM) is defective – the control box connections need checking |
F0 242 | Control box or the heat control module (HCM) is defective – the HCM and control box connections need to be checked |
B7 257 | Control box or the heat control module HCM) is defective- the HCM and control box connections need to be checked |
F0 258 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
EH 258 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
F1 259 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
F0 262 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
F1 263 | Control box or the heat control module (HCM) is defective – HCM or control box connections need to be checked |
F0 272 | Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing |
F0 280 | Control box or the heat control module (HCM) is defective – control box and connections need checking or HCM might not be inserted properly and need replacing |
F0 290 | Control box is defective – HCM needs checking as it might not be inserted properly or need replacing |
328 | Internal error with the mains voltage – frequency may be inconsistent |
235 | Incompatible heat control module (HCM) software versions – control box needs latest software |
356 | Low mains voltage – the voltage may be interrupted or inconsistent and needs checking |
360 | Heat control module (HCM) invalid – the inserted HCM does not correspond with the control box |
A8 362 | Low mains voltage – the voltage may be interrupted, inconsistent or heat control module (HCM) invalid |
CC 800 | Outdoor sensor defect available when accessory outdoor sensor is connected |
A1 281 | Pump stock or running dry |
E9 224 | Flue or high limit thermostat activated |
D4 341 | Primary flow temperature rising too fast |
Worcester Bosch GB162 Boiler Error Codes
Fault Description | System Behaviour |
---|---|
208 | The boiler is in chimney sweep mode |
200 | The boiler is in heating mode |
201 | The boiler is in domestic hot water (DHW) mode |
202 | The boiler is waiting – there was a heat demand from the on off or modulating control |
203 | The boiler is on standby |
204 | The boiler is waiting – the actual temperature is higher than the calculated or selected boiler temperature |
212 | The temperature recorded by the flow temperature sensor or the safety sensor is rising too quickly |
226 | Diagnosis tool was connected and is now locked out |
260 | The flow temperature sensor is not detecting a rise in temperature following a burner start |
265 | The boiler is waiting in response to a heat demand – the boiler regularly switches to partial load |
268 | Component test phase |
270 | The boiler is modulating upwards |
283 | The boiler is preparing for a burner start – the fan and pump are activated |
284 | The gas valve is switched |
305 | The boiler is waiting for domestic hot water (DHW) operation to end |
235 | The KIM (boiler identification module) is too new for the burner control unit |
360 | The KIM that has been fitted is not compatible with the burner control unit |
9A 361 | The burner control unit that has been fitted is not compatible with the KIM (boiler identification module) |
9U 233 | The burner control unit or KIM (boiler identification module) is faulty |
A3 317 | Short circuit in the flue gas temperature sensor contacts |
B7 257 | The burner control unit or the KIM (boiler identification module) is faulty |
C1 264 | No control signal or power supply to the fan during operation |
C4 273 | The boiler was switched off for a maximum of 2 minutes because it had been operating continuously for more than 24 hours |
C6 215 | The fan speed is too high |
C6 216 | The fan speed is too low |
C7 214 | The fan does not run during the start phase |
C7 217 | The fan speed is irregular when starting up |
CE 207 | Water pressure is too low |
CE 266 | Pump test failed |
D1 240 | The contacts of the boiler return temperature sensor have been short circuited |
D1 241 | The contacts of the boiler return temperature sensor have been interrupted |
D3 232 | The external switching contact has opened |
D4 213 | The actual temperature recorded by the flow temperature sensor or return temperature sensor is rising too quickly |
D4 271 | Actual temperature differential between flow and safety temperature sensor is too high |
D4 286 | The boiler return temperature sensor has detected a return temperature higher than 105°c |
E2 222 | Short circuit in the flow temperature sensor contacts |
E2 223 | The flow temperature sensor contacts have been interrupted |
E5 218 | The temperature captured by the flow temperature sensor exceeded 105°c |
E9 210 | The temperature measured by the flue gas sensor is too high and is open |
E9 219 | The safety temperature sensor has captured a temperature in excess of 105°C |
E9 220 | The contacts for the safety temperature sensor have shorted or the safety temperature sensor has detected a temperature higher than 130°c |
E9 224 | The contacts of the safety temperature sensor have been interrupted |
E9 276 | The temperature flow sensor has measured a temperature in excess of 95°c |
E9 277 | The safety temperature sensor has measured temperature in excess of 95°c |
E9 285 | The boiler return temperature sensor has measured a temperature higher than 95°c |
E9 318 | The flue gas temperature sensor contacts have been interrupted |
EA 227 | An insufficient ionisation current was measured following ignition of the burner |
EA 229 | The ionisation current detected by the system during the burning phase was insufficient |
EA 234 | The contacts of the gas valve have been interrupted |
EA 261 | The burner control unit is faulty |
EA 269 | The ignition device has been activated for too long |
F0 238 | The burner control unit KIM (boiler identification module) is faulty |
F0 239 | The burner control unit KIM (boiler identification module) has an error. Cabling might have poor contact breaks and pinching or the plug and wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
F0 242, F0 243. F0 244. F0 245, F0 246. F0 247, F0 248, F0 249, F0 250, F0 251, F0 252, F0 253, F0 255, F0 259, F0 263, F0 267, F0 272 | The burner control unit (KIM) is faulty – the wiring of the burner control unit needs checking, also check the operating characteristics of the boiler by replacing the burner control unit. |
F0 278 | The sensor test has failed – cabling and plug sensors need checking |
F0 279 | The burner control unit, or KIM, is faulty – control unit may need replacing |
F0 280 | The burner control unit is faulty |
F0 287 | The burner control unit, or KIM, has an error |
F0 290 | The burner control unit, or KIM, is faulty |
F7 228 | An ionisation current was measured before the burner started |
F7 328 | A brief power failure has occurred |
FA 306 | An ionisation current was measured after the burner went out |
FD 231 | The mains voltage was interrupted during an interlocking fault |
EC 256 | The burner control unit has an error |
EH 258 | The burner control unit is faulty – check the plug and wiring of the burner control unit. |
H07 | The current water pressure is too low, limiting the performance in heat mode as well as domestic hot water (DHW) mode |
HrE | The boiler keeps resetting |
rE | The boiler resets |
Worcester Bosch CDI Highflow Combi Boiler Error Codes
A light on your boiler will flash to indicate that there is a fault. Depending on the type of fault, the light will flash in a different sequence.
There will be 4 quick flashes followed by a 5 second gap when the light is off and finally a series of longer flashes. The number of long flashes tells you which fault the boiler has.
Fault Description | System Behaviour |
---|---|
Light off | No boiler demand |
Light on | Heating demand on boiler is OK |
1 flash 5 seconds off | No ionisation detected after ignition |
2 flashes 5 seconds off | Loss of ionisation signal during operation |
3 flashes 5 seconds off | Gas valve error |
4 flashes 5 seconds off | First safety timing error / ignition timing error |
5 flashes 5 seconds off | Ionisation detected after burner stopped Gas valve EV2 leak test failed Gas valve EV1 leak test failed Ionisation current detected before burner start Gas valve error Ionisation sensor shorted |
4 flashes 5 second gap 1 long flash | Sensor test failed |
4 flashes, 5 second gap, 2 long flashes | Safety temperature too high |
4 flashes, 5 second gap, 3 long flashes | Max safety thermostat activated |
4 flashes, 5 second gap, 4 long flashes | Return temperature too high |
4 flashes, 5 second gap, 5 long flashes | Flow temperature too high – supply sensor exceeded 110°c |
1 long flash, 4 quick flashes, 5 second gap, 1 long flash, 4 quick flashes | Heating control module (HCM) defective |
2 long flashes, 4 quick flashes, 5 second gap, 2 long flashes, 4 quick flashes | Fan running too fast Fan running too slow No airflow after defined period of time Fan not running |
3 long flashes, 4 quick flashes, 5 second gap, 3 long flashes, 4 quick flashes | Mains voltage interrupted after locking error |
4 long flashes, 4 quick flashes, 5 second gap, 4 long flash, 4 quick flashes | Internal control board faults |
5 long flashes, 4 quick flashes, 5 second gap, 5 long flash, 4 quick flashes | All other miscellaneous faults – reset the boiler by turning the control knob anti-clockwise to the reset position |
Worcester Bosch Greenstar Ri Boiler Error Codes
Fault Description | System Behaviour |
---|---|
No light | No power at control board |
Light on | Appliance on but not operating during demand |
Slow flash ( mostly off flashes on) | Ignition lockout |
Slow flash ( mostly on flashes off) | Flue overheat or heat exchanger overheat |
Fast flash | Volatile lockout sensor fan or code plug |
2 pulses | Check service mode switch is in minimum position |
5 pulses | Check service mode switch is in max position |
Worcester Bosch Greenstar 8000 Boiler Error Codes
Fault Description | System Behaviour |
---|---|
200 O | Boiler in heating mode |
201 O | Boiler in hot water mode |
202 O | Boiler in anti-cycle mode |
203 0 | Boiler in standby – no heat energy demand |
204 O | Current primary water temperature higher than set value |
208 0 | Chimney sweep demand |
224 V | Safety temperature limiter has tripped – top-up water until the reset pressure is reached |
227 V | No flame signal after ignition burner control unit could need replacing |
228 V | Flame signal without flame present – air/gas ratio control valve may need replacing as might the ionisation cable |
305 0 | Boiler in hot water anti-cycle mode |
306 V | Flame signal after closing the fuel supply – the air/gas ratio control valve might need replacing |
360 V | Incompatible code plug – check if a correct code plug is installed and exchange or reconnect code plug |
815 W/B | Low loss header temperature sensor faulty – check the sensor port or check the differential sensor for incorrect installation position or breakage |
1010 O | No BUS communication cable, EMS-Bus isn’t connected or damaged – connect the cable for the EMS-Bus or replace the damaged cable exchange fuse |
1017 W | Water pressure too low – the water needs topping up and the vent system or pressure sensor may need replacing |
1021 B | Hot water temperature sensor is defective – the plug to the hot water temperature sensor may not be connected |
1022 B | Hot water storage temperature sensor is defective – connect the plug to the hot water temperature sensor correctly, mount the hot water temperature sensor correctly or replace the hot water temperature sensor |
1037 W | Outside temperature sensor is defective – check the connecting lead |
1065 B | Pressure sensor defective or not connected – check pressure sensor connection as it may need replacing |
1068 W | Outside temperature sensor defective – check the connecting lead |
1073 W | Short circuit of the flow temperature sensor – the temperature sensor may need replacing |
1074 W | No signal from the flow temperature sensor available – connect the plug to the flow temperature sensor correctly or temperature sensor could need replacing |
1075 W | Short circuit of the temperature sensor at the heating block – temperature sensor may need replacing |
1076 W | No signal from the temperature sensor at the heating block available – replace the temperature sensor, the connecting lead or the control unit |
2920 V | Error with the flame monitoring |
2924 V | No feedback from the modulating gas valve. The gas valve relay is defective – press the reset button and apply burner start, wait to see if fault reoccurs, if it does the gas valve needs replacing |
2925 V | Feedback from the modulating gas valve is too low |
2927 B | Flame failed during burner operation. Open the main shut off valve, shut down the appliance and check gas line, replace the ionisation electrode, set burner correctly and minimum rated load, check the integrity flue system and if the interconnected room air supply is too small, or the size of the ventilation opening is too small, clean the heating block on the flue gas side or replace the control unit/burner control unit |
2946 V | Incorrect code plug detected – the code plug needs replacing |
2948 B | No flame signal. With low output the burner starts automatically after cleaning. If the fault occurs repeatedly, the setting of the CO2 valves need checking |
2950 B | No flame signal. Following starting procedure the burner starts automatically. After cleaning set the correct gas / air ratio correctly |
2963 B | Signal from flow and heat exchanger temperature sensor outside the permissible range – the connecting lead needs connecting correctly |
2964 B | Flow rate in heat exchanger is too low |
2965 B | Flow temperature too high |
2966 B | Flow temperature rise in heat exchanger too rapid |
2967 B | Flow / heat exchanger temperature sensor differential too great |
2970 B | Pressure drop in heating system too rapid |
2971 B | System pressure too low – the heating system needs venting or water needs topping up until the preset pressure is reached. Replace the cable to the pressure sensor replace the pressure sensor |
Worcester Bosch Error Code EA 229 or D5
If you’re seeing the error code EA 229 or D5 on your Worcester Bosch boiler, this means that the condensate pipe is frozen. This happens due to the condensate pipe running outside, however this is an issue that you could fix yourself if you feel confident enough, you can find out how in our handy guide.
- View the Boiler Guide home of Worcester Bosch
- See the common problems and get repair advice for your Worcester Bosch boiler
Shown below are Worcester Bosch Fault Codes. Please note some faults may be applicable only to certain models or types of boiler.
Display Code | Repair | Description | Remedy | Resources |
---|---|---|---|---|
A1 | Link | Pump has run dry or pump has stalled/seized. | Check for water leaks. Free the pump or replace. | |
A7 | Link | Hot water NTC sensor defective. | Check hot water NTC sensor and connecting lead for circuit breaks/short circuits. | |
A8 | Link | Break in communication to TD200 or/and RT10. | Check electrical connections. | |
b1 | Link | Code plug not detected. | Insert code plug correctly, test and replace if necessary. | |
C6 | Link | Fan speed too low. | Check fan lead and connector, and fan; replace as necessary. | |
E2 | Link | CH flow NTC sensor defective. | Check CH flow NTC sensor and connecting lead. | |
E9 | Link | Safety temp. limiter in CH flow has tripped. | Check system pressure, check safety temp. limiters, check pump operation, check fuse on pcb, bleed appli- ance. | |
EA | Link | Flame not detected. | Is gas cock turned on? Check gas supply pressure, power supply, igniter electrode and lead, ionisation sensing electrode and lead, flue duct and C02 level. | |
F0 | Link | Internal error. | Check electrical connector contacts, programmer inter- face module ignition leads are not loose; replace pcb if necessary. | |
F7 | Link | Flame detected even though appliance switched off. | Check electrode assembly, dry pcb. Flue clear? | |
FA | Link | Flame detected after gas shut off. | Check gas valve and wiring to gas valve. Clean conden- sation trap and check electrode assembly. Flue clear? | |
Fd | Link | Reset button pressed by mistake. | Press reset button again. | |
-¦¦- and XX | Link | Siphon fill mode | Wait approx 15 mins |