At Repair Network, you have access to a full list of experienced gas-safe engineers that can carry out repairs and service for your Worcester boiler.
We offer a nationwide coverage, fixed cost repairs, a one-year guarantee and same or next-day service.
Worcester offers a range of models that include combi, system and regular boilers.
A leading domestic boiler provider in the UK for 50 years, Worcester was founded in the UK in 1962 and became part of the Worcester Bosch Thermotechnology division of the Worcester Bosch Group in 1996. Continued excellence means plenty of happy customers due to the brand’s commitment to the latest technology and newest products. Most recently, Worcester has focussed on the production of environmentally-friendly boilers and heating systems, including utilising solar power.
Worcester boilers have been recommended many times over the years by Which? And the company has also received a Royal Warrant from Queen Elizabeth II for its many years of supplying boilers to Sandringham Estate.
Based in the city of the same name where most operations are conducted, Worcester also has a site in Clay Cross Derbyshire, where its oil boilers are manufactured.
Worcester backs its products with a range of guarantee and service options, depending on which model and package you select.
Book a certified technician with the tools and experience to repair all your Worcester Boiler!
When your boiler breaks down, you need a fast and reliable service that is also affordable and efficient. Repair Network is dedicated to its customers, providing prompt service by registered, trained and experienced technicians.
You can choose from appointment times that fit with your schedule and keep you from having to live without a boiler for too long; a situation that can be frustrating and inconvenient. We offer same and next day service, so you won’t have to wait long for a boiler repair.
In addition to technicians who are gas registered with experience working on your boiler brand, we also offer nationwide coverage and a promise to perform all repairs safely.
We always aim to complete a boiler repair, preventing the expense of replacing it. Our repair, not replace policy comes with a one-year guarantee.
You can check our track record any time by looking at our reviews on Trustpilot.
Customer service is our number one goal and with that comes transparent pricing.
Our fixed cost fees keep you from finding any hidden fees in your boiler repair costs. This fixed cost includes brand-approved parts and labour.
You’ll also have the peace of mind that comes with our one-year guarantee, should anything go wrong.
If your engineer cannot repair your boiler, we will provide a free, no-obligation quote for replacement and installation of a new boiler.
Determine the model of your Worcester boilers and look to the ahead for the various error codes and what they mean.
Worcester Bosch boilers categorise their error codes into the following:
| Fault Description | Codes that will appear on your boiler |
|---|---|
| Blocking Error | The boiler will stop operating but no fault code will appear. You can access the cause code by pressing the spanner/return button. The condition will clear once the fault clears. For instance, if the boiler is waiting for an area to cool, the error will clear automatically once the associated area has cooled down. |
| Locking Error | The boiler will flash a warning triangle and a fault code. It will also show a static cause code. You’ll need to press the boiler reset button to clear the code, but only after the boiler has been fixed. |
| Fault Error | The boiler will display an alphanumeric fault code to indicate the fault group. |
| Cause Error | A three-digit number that can be accessed via the info menu by pressing the spanner/return button during a blocking error or when in normal operating status. The cause code should flash on the display during a locking error. |
| Maintenance Code | A maintenance code is displayed with the letter H followed by a number. The fault won’t stop the boiler from working but it tells you that the boiler needs to be looked at by a qualified engineer. |
| Fault Description | System Behaviors |
|---|---|
| EA338 | A leak somewhere, either within your boiler or around the system. |
| A281 | A leak somewhere, either within your boiler or around the system. |
| A41 | Boiler making loud noises – likely due to a faulty pump or heat exchanger. |
| EA227 | Boiler has locked out. This will be to prevent any further damage occurring and to remove potential danger. |
| E5218 | Boiler has overheated. |
| E5332 | Boiler has overheated. |
| E9219 | Boiler has overheated. |
| E9224 | Boiler has overheated. |
| D1286 | Boiler has overheated. |
| EA225 | Condensate pipe is blocked. |
| D5 | Condensate pipe is blocked. |
The Worcester Bosch CDi Classic are a range of combi boilers available in 29 CDi, 34 CDi, 38CDi and 42CDi.
| 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. |
The Highflow is available in two models – the Greenstar Highflow 440Cdi and the Greenstar Highflow 550Cdi.
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 |
| 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 pre-set pressure is reached. Replace the cable to the pressure sensor replace the pressure sensor |
| 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 | 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 pre-set pressure is reached. Replace the cable to the pressure sensor replace the pressure sensor |
| Boiler Model | Fault Description / Code | Reason |
|---|---|---|
| Worcester Bosch Greenstar 4000 30 | 1021 | Cylinder charging or hot water temperature sensor faulty. Turn the appliance off and back on again. The hot water sensor has been changed if an open or short circuit or refitted to the pipe if it has fallen off. |
| Worcester Bosch 4000 | 224 | Software issue. Arrange a visit from a Worcester Bosch engineer to reset the boiler/PCB. |
