BoilerFaultCodes.com

Worcester Bosch Greenstar 25 HE Combi Fault Codes

Combi Natural GasLPG 25 kW 2005-2007 Discontinued
GC Number: 47-114-41

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

2.5
Your boiler has shut down because the water in the heating system has become too hot, usually due to a lack of circulation or a blockage.
May be DIY safe · £100-£280
2.6
Your boiler has detected that the temperature is changing too quickly or slowly between the flow and return pipes, causing it to shut down to prevent damage.
Gas Safe engineer required · £120-350
A8
Your boiler’s internal computer and main controls have lost their connection, preventing the system from starting up.
Gas Safe engineer required · £180-450

All 20 fault codes

Code Severity Plain English
2.4 Low Your boiler is temporarily pausing its burner to prevent it from switching on and off too frequently, which protects the internal parts from unnecessary wear.
2.5 High Your boiler has shut down because the water in the heating system has become too hot, usually due to a lack of circulation or a blockage.
2.6 High Your boiler has detected that the temperature is changing too quickly or slowly between the flow and return pipes, causing it to shut down to prevent damage.
5.0 Low Your boiler is operating at its maximum heating capacity and has entered a temporary monitoring state, which is usually part of normal operation or a simple setting adjustment.
6.8 Medium Your boiler is confused by how long it is taking to heat your hot water and is stuck in a constant cycle.
A7 Medium Your boiler is struggling to accurately measure the temperature of your hot water, which usually prevents it from heating the water correctly.
A8 High Your boiler’s internal computer and main controls have lost their connection, preventing the system from starting up.
AC High Your boiler's internal computer is having trouble communicating with one of its main control parts, meaning the system cannot run.
b1 High Your boiler has lost its internal identity chip and can no longer recognize its own settings or model type.
C1 High Your boiler has stopped working because the internal fan is not spinning fast enough to safely clear away exhaust fumes.
C4 High Your boiler's fan is not spinning fast enough to clear out exhaust fumes, so the system has shut down as a safety precaution.
C6 High Your boiler has detected that its internal fan is spinning at the wrong speed, which means it cannot safely exhaust fumes and has stopped working as a result.
E2 High Your boiler has detected a problem with the internal sensor that monitors the temperature of the water heading to your radiators, 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 temperature has become dangerously high.
EA High Your boiler is failing to detect a flame and has safely shut down to prevent unburned gas from flowing.
F0 High Your boiler's computer may have encountered a temporary glitch or a more serious internal component failure.
F7 High Your boiler thinks there is still a flame burning even though it has commanded the gas to turn off.
FA Emergency Your boiler thinks it still sees a flame even though the gas supply has been turned off, which is a safety conflict.
Fd Low Your boiler is simply letting you know that the 'Reset' button was pressed for too long or by accident.
P1, P2, P3, P1... Low Your boiler is currently going through a startup and self-test sequence, which usually happens after it has been switched back on or reset.

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 specific internal link that tells it how to operate safely.

Worcester Bosch Greenstar 25 HE Combi 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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