BoilerFaultCodes.com

Worcester Bosch Greenstar 25HE Fault Codes

Combi Natural GasLPG 25 kW 2003-2005 Discontinued
GC Number: 47-311-32

Replaced by: Greenstar 25i

The fault code is already on your display

Note it down before pressing reset — resetting clears the code immediately. How to read fault codes →

Most common fault codes

5.2
Your boiler has detected a problem with its electronic ignition system, meaning it cannot process the command to start the flame safely.
Gas Safe engineer required · £250-£450
9.3
Your boiler’s internal computer has encountered a memory error and cannot safely operate the heater.
Gas Safe engineer required · £280-450
A1
Your boiler is trying to work but cannot detect enough water moving through the system to operate safely.
May be DIY safe · £100-350

All 26 fault codes

Code Severity Plain English
0.0 Low This is not an active fault code, but a menu setting used by engineers to view the history of previous problems with your boiler.
5.2 High Your boiler has detected a problem with its electronic ignition system, meaning it cannot process the command to start the flame safely.
9.3 High Your boiler’s internal computer has encountered a memory error and cannot safely operate the heater.
A1 High Your boiler is trying to work but cannot detect enough water moving through the system to operate safely.
A5 High Your boiler's temperature sensor responsible for monitoring stored hot water has developed a fault, preventing it from reading the temperature correctly.
A7 Medium Your boiler is struggling to accurately measure the temperature of your hot water, which usually means it cannot provide a consistent warm flow to your taps.
A8 High Your boiler's internal computer has lost contact with its control panel or external sensors, meaning it cannot receive the instructions it needs to work.
AC High Your boiler's main internal computer has lost communication with one of its electronic parts, meaning it cannot operate until the connection is restored.
Ad Medium Your boiler is unable to communicate with its external hot water tank sensor, meaning it doesn't know the temperature of your water.
b1 High Your boiler's main control chip is either loose or has failed, which means the computer can't identify the specific model to operate safely.
C1 High Your boiler has stopped working because the internal fan isn't spinning fast enough to safely clear away exhaust fumes.
C4 High Your boiler's fan is spinning faster than it should, which means the system has stopped running to prevent any damage or unsafe operation.
C6 High Your boiler has stopped working because the fan that clears away waste gases has failed to start or is spinning too slowly.
E2 High Your boiler's internal thermometer that monitors water temperature has stopped working correctly, causing the system to shut down for safety.
E9 High Your boiler has shut down because a sensor has detected that the internal water or exhaust gases have become dangerously hot.
EA High Your boiler has failed to light because it cannot detect a flame, which most likely means there is an issue with the gas supply or a part that ignites the fuel.
F0 High Your boiler's computer brain has suffered a serious internal glitch and is unable to communicate with its own sensors or controls.
F7 Emergency Your boiler thinks a flame is still burning inside even after it has been told to turn off, which is a safety conflict.
FA Emergency Your boiler is still detecting a flame even though it has tried to turn the gas supply off, which is a safety conflict.
FC High Your boiler's main control panel has lost communication with the internal computer, meaning the display cannot show information or process commands.
Fd Low Your boiler is simply confused because the reset button was held down for too long or pressed when it wasn't needed.
P1 High Your boiler is repeatedly trying and failing to complete its ignition process, essentially getting stuck in a loop during startup.
P1, P2, P3, P1... Low Your boiler is simply going through its normal startup and self-test sequence after being turned on or reset.
P2 Low Your boiler is currently going through its normal starting process but is taking a little longer than usual to fully ignite.
P3 Low Your boiler is simply showing that it is going through its normal starting process and trying to fire up.
r1 Low Your boiler is currently resetting its internal settings back to the way they were when it first left the factory.

Status & diagnostic codes

These codes indicate your boiler's operating state or a diagnostic reading — not necessarily a fault. Status codes (S.) mean normal operation; diagnostic codes (D.) are informational readings used by engineers.

Code Type Description
d3 Diagnostic Your boiler has lost its connection to an external safety device or a plug-in controller, causing it to stop running as a safety precaution.

Worcester Bosch Greenstar 25HE is discontinued — time for a new one?

Parts for discontinued models can be hard to find and expensive. A new A-rated boiler could save you money on both repairs and energy bills.

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