BoilerFaultCodes 2.4
Your boiler is currently taking a mandatory rest period to prevent the system from overheating, which is a normal safety feature after it has been running for a while.
Worcester Bosch Greenstar R29 40 HE Fault codes & diagnostics
25 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Regular Natural Gas 40 kW 2003-2006 Discontinued
GC Numbers 41-311-6041-311-61
Download the Worcester Bosch Greenstar R29 40 HE manual
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Versions & GC numbers
The fault code is already on your display
Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →
Severity at a glance
Each cell = one fault code. Hover to identify. 4 Emergency
15 High
6 Low
Which version do you have?
The GC number on your boiler's data badge identifies the exact appliance and production years, as recorded in the UK Product Characteristics Database.
| GC number | Appliance (register name) | Produced |
|---|---|---|
| 41-311-60 | Greenstar R 29 HE Conventional | 2003–2006 |
| 41-311-61 | Greenstar R 40 HE Conventional | 2003–2006 |
Just want the most common Worcester Bosch Greenstar R29 40 HE faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 25 documented codes
Tap any card for details
5.2 Your boiler is failing to light the flame, which means your heating and hot water have stopped working.
Your boiler is failing to light the flame, which means your heating and hot water have stopped working.
Parts commonly replaced
- Ignition electrode
- Ignition lead
- Gas valve
- Printed Circuit Board (PCB)
Related codes
9.3 Your boiler's electronic control system responsible for safely lighting the gas flame has developed a fault and cannot start the heating process.
Your boiler's electronic control system responsible for safely lighting the gas flame has developed a fault and cannot start the heating process.
Parts commonly replaced
- Printed Circuit Board (PCB)
- Wiring harness
Related codes
24 V fuse blown Your boiler has stopped working because an internal safety fuse has tripped to protect its electrical system from an unexpected power surge or short circuit.
Your boiler has stopped working because an internal safety fuse has tripped to protect its electrical system from an unexpected power surge or short circuit.
Parts commonly replaced
- 24V fuse
- Printed Circuit Board (PCB)
- Wiring harness
Related codes
A8 Your boiler's internal electronic controls have lost their connection, preventing the heating and hot water from operating correctly.
Your boiler's internal electronic controls have lost their connection, preventing the heating and hot water from operating correctly.
Parts commonly replaced
- Control Board (PCB)
- Wiring Harness
Related codes
AC Your boiler's computer is failing to communicate with its internal control panel, meaning the system cannot safely operate.
Your boiler's computer is failing to communicate with its internal control panel, meaning the system cannot safely operate.
Parts commonly replaced
- Control module
- Wiring harness
- Main printed circuit board
Related codes
Ad Your boiler has identified an issue with the weather compensation sensor, meaning it is currently struggling to automatically adjust its temperature based on the outdoor weather conditions.
Your boiler has identified an issue with the weather compensation sensor, meaning it is currently struggling to automatically adjust its temperature based on the outdoor weather conditions.
Parts commonly replaced
- Outdoor temperature sensor
- Wiring harness
b1 Your boiler has lost its connection to an internal system component, meaning it cannot properly communicate with its own controls to function.
Your boiler has lost its connection to an internal system component, meaning it cannot properly communicate with its own controls to function.
Parts commonly replaced
- Keyed plug / Coding plug
- PCB
Related codes
C1 Your boiler is struggling to push air through its internal system, which prevents it from safely igniting and providing heating or hot water.
Your boiler is struggling to push air through its internal system, which prevents it from safely igniting and providing heating or hot water.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Flue sensor
Related codes
C6 Your boiler has detected that the internal exhaust fan is spinning faster than it should, causing the system to stop working to keep your home safe.
Your boiler has detected that the internal exhaust fan is spinning faster than it should, causing the system to stop working to keep your home safe.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board
Related codes
Showing 11–20 of 25
d3 Your boiler is failing to start because it is not receiving a signal from your thermostat or internal control link to turn on the heating.
Your boiler is failing to start because it is not receiving a signal from your thermostat or internal control link to turn on the heating.
Parts commonly replaced
- External controls/thermostat
- Wiring harness
- PCB
Related codes
E2 Your boiler's internal thermometer is not sending a signal, so the system is shutting down to prevent overheating because it doesn't know how hot the water is.
Your boiler's internal thermometer is not sending a signal, so the system is shutting down to prevent overheating because it doesn't know how hot the water is.
Parts commonly replaced
- NTC Flow Temperature Sensor
- Wiring harness / Sensor connector
Related codes
E9 Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent any damage or safety issues.
Your boiler has detected that it is getting too hot and has automatically shut itself down to prevent any damage or safety issues.
Parts commonly replaced
- NTC temperature sensor
- Central heating pump
- Heat exchanger
Related codes
EA Your boiler is trying to start but the flame is failing to light or stay on, so it has shut down as a safety precaution.
Your boiler is trying to start but the flame is failing to light or stay on, so it has shut down as a safety precaution.
Parts commonly replaced
- Ignition electrode
- Gas valve
- Condensate trap
- Printed Circuit Board
Related codes
F7 Your boiler has detected that the internal flame is still burning even though it should have turned off, which is a significant safety precaution.
Your boiler has detected that the internal flame is still burning even though it should have turned off, which is a significant safety precaution.
Parts commonly replaced
- Gas valve
- Printed Circuit Board (PCB)
Related codes
FA Your boiler has detected that a flame is still burning even though it has tried to turn the gas supply off, which is a safety concern.
Your boiler has detected that a flame is still burning even though it has tried to turn the gas supply off, which is a safety concern.
Parts commonly replaced
- Gas valve
- Printed Circuit Board (PCB)
- Ionisation electrode
Related codes
Fan speed too low Your boiler has identified that the internal fan is moving too slowly, so it has safely shut itself down to prevent it from operating incorrectly.
Your boiler has identified that the internal fan is moving too slowly, so it has safely shut itself down to prevent it from operating incorrectly.
Parts commonly replaced
- Fan assembly
- Wiring harness
Related codes
Fault Your boiler is struggling to burn gas cleanly, resulting in internal vibrations or rumbling sounds that suggest a combustion issue.
Your boiler is struggling to burn gas cleanly, resulting in internal vibrations or rumbling sounds that suggest a combustion issue.
Parts commonly replaced
- Gas valve
- Burner seal
- Ignition electrode
- Air/flue seals
Related codes
Fd Your boiler is simply indicating that the reset button has been pressed briefly during normal operation, rather than it being a sign of a broken part.
Your boiler is simply indicating that the reset button has been pressed briefly during normal operation, rather than it being a sign of a broken part.
What to check first
- Wait for the boiler to return to its normal display mode automatically
- If the boiler does not resume, switch it off at the fused spur
- Wait 30 seconds and switch the power back on to clear the notification
Flame not detected Your boiler has stopped working because it cannot light the flame required to heat your water and home.
Your boiler has stopped working because it cannot light the flame required to heat your water and home.
Parts commonly replaced
- Ignition electrode
- Ionisation probe
- Gas valve
Related codes
Showing 21–25 of 25
Flow NTC sensor defective Your boiler's temperature gauge is faulty, meaning it cannot correctly measure how hot the water is and has stopped working to prevent potential overheating.
Your boiler's temperature gauge is faulty, meaning it cannot correctly measure how hot the water is and has stopped working to prevent potential overheating.
Parts commonly replaced
- Flow NTC Temperature Sensor
- Wiring harness
Related codes
Internal error Your boiler's computer is experiencing a communication failure, causing it to shut down to prevent incorrect operation.
Your boiler's computer is experiencing a communication failure, causing it to shut down to prevent incorrect operation.
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Interface Module
Related codes
P1
Your boiler is currently performing an automatic internal check or scheduled system routine and is temporarily unavailable for normal operation.
P2 Your boiler is currently performing a brief startup check to ensure all internal systems are communicating correctly before it begins normal operation.
Your boiler is currently performing a brief startup check to ensure all internal systems are communicating correctly before it begins normal operation.
Related codes
P3
Your boiler is currently performing an automated internal calibration or maintenance check and will resume normal operation once finished.
Status & diagnostic codes 10 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
10 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
.0 Diagnostic Your boiler is displaying a status code that simply invites you to view the last recorded error message stored in its memory. 1. Status Your boiler is currently operating at its lowest possible power setting, which may prevent it from heating your home or water effectively. 2. Diagnostic Your boiler is currently running at its absolute maximum capacity to meet a high demand for heat or hot water, and the system is flagging this as a status notification rather than a breakdown. 2.0 Status Your boiler is operating normally and there is no fault present. 2.5 Diagnostic Your boiler has shut down because it is getting too hot and cannot circulate the heat through your radiators effectively. 2.6 Diagnostic Your boiler is struggling to maintain a consistent temperature because the difference between the actual water temperature and the target temperature is outside of the expected range. 3.3 Diagnostic Your boiler is struggling to detect the flame needed to heat your home, so it has safely shut itself down to prevent any gas build-up. 5.0 Diagnostic Your boiler is currently running at its maximum heating capacity and is effectively notifying you that it is working hard to meet a high demand for warmth. fI- Status Your boiler is performing a routine self-check and safety fill of its condensation system because the power was recently switched off and on. Last fault stored Diagnostic Your boiler has stored a record of a previous error as part of its internal history log, which does not necessarily mean there is an active breakdown occurring right now.