Worcester Repair Specialist

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.

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Worcester Boilers

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.

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Require some form of repairs!

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03333449104

Available 9 AM to 7 PM

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Why Repair Network Nationwide?

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.

What we Cover and What We Don’t

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.

What are the error codes Worcester boiler and what do the mean?

Determine the model of your Worcester boilers and look to the ahead for the various error codes and what they mean.

Find your Error Code

Worcester Bosch Boiler Error Codes

Worcester Bosch boilers categorise their error codes into the following:

Fault DescriptionCodes 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.

Common Worcester Bosch Boiler Fault Codes

Fault DescriptionSystem 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.

Worcester Bosch CDI Classic Combi Boiler Error Codes

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.

Worcester Bosch CDI Highflow Combi Boiler Error Codes

The Highflow is available in two models – the Greenstar Highflow 440Cdi and the Greenstar Highflow 550Cdi.

Fault DescriptionSystem 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 Boiler Error Codes

Fault DescriptionSystem 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 Greenstar 25/30 Si Combi Boiler Error Codes

Fault DescriptionSystem 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 Greenstar 27/30 I System Boiler Error Codes

Fault DescriptionSystem 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 DescriptionSystem 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 DescriptionSystem 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 Greenstar Ri Boiler Error Codes

Fault DescriptionSystem 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 Code

Fault DescriptionSystem 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

Worcester Bosch Greenstar 2000 Boiler Error Code

Fault DescriptionSystem 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

Worcester Bosch Greenstar 4000 Boiler Error Code

Boiler ModelFault 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.