BoilerFaultCodes.com

Worcester Bosch 24/28CDi II RSF Fault Codes

Combi Natural Gas 24-28 kW 2003-2007 Discontinued
GC Numbers: 47-108-1047-108-11

Replaced by: Greenstar 25/30i

This boiler uses indicator light combinations

Note which lights are on, off, or flashing and at what speed. Match the combination to the table below. Do not reset until you have noted the pattern. How to read fault codes →

Most common fault codes

Central heating and domestic hot water demand indicators BOTH FLASHING SLOW (once per second)
Your boiler has sensed it is getting too hot and has shut itself down for safety.
May be DIY safe · £120-350
Central heating demand indicator FLASHING FAST (five times per second)
Your boiler has detected an internal computer or electrical fault that has caused it to stop working for safety.
Gas Safe engineer required · £150-£450
Central heating demand indicator FLASHING SLOW (once per second)
Your boiler has tried to light several times but failed, so it has safely shut itself down for your protection.
May be DIY safe · £100-£350

All 29 fault codes

Code Severity Plain English
Central heating and domestic hot water demand indicators BOTH FLASHING SLOW (once per second) High Your boiler has sensed it is getting too hot and has shut itself down for safety.
Central heating demand indicator FLASHING FAST (five times per second) High Your boiler has detected an internal computer or electrical fault that has caused it to stop working for safety.
Central heating demand indicator FLASHING SLOW (once per second) High Your boiler has tried to light several times but failed, so it has safely shut itself down for your protection.
Domestic hot water demand indicator FLASHING FAST (five times per second) Emergency Your boiler has detected a safety issue with how it clears exhaust fumes, causing it to shut down to prevent dangerous gases from entering your home.
E00-711 High Your boiler is struggling to transfer heat to your hot water because a key internal component is likely blocked or damaged.
E00-716 High Your boiler has detected a serious problem with the fan that safely removes exhaust gases, meaning the system has shut down for your safety.
E00-720 High Your boiler has detected a fault with the burner unit, meaning it cannot safely ignite or maintain a flame to provide heat or hot water.
E00-721 High Your boiler has detected a serious internal problem with the gas burner system, causing it to shut down for safety.
E00-722 High Your boiler's main control computer has developed an internal electrical fault and can no longer safely operate the system.
E00-730 High Your boiler has detected a problem with how it moves air and exhaust gases, which has caused it to shut down for safety.
E00-737 High Your boiler's burner has encountered a serious ignition or combustion failure, meaning it cannot safely light to provide heat or hot water.
E00-738 High Your boiler has detected a critical internal fault with the burner system that regulates the fuel supply, meaning the appliance cannot ignite safely.
E00-741 High Your boiler has detected an issue with the internal burner assembly components, likely related to the incorrect gas injection setup for your fuel type.
E01-840 High Your boiler has lost water pressure, and the internal component used to refill it is likely disconnected or faulty.
E80-450 High Your boiler has detected a failure with the internal gas control valve, meaning it cannot safely ignite to provide heating or hot water.
E80-451 High Your boiler has detected a specific internal electronic fault with the valve that controls the gas supply, meaning the appliance cannot ignite safely and will remain shut down.
E00716 High Your boiler has detected an internal issue with the component meant to release trapped air from the system, which may prevent it from heating properly.
E01612 High Your boiler has failed to detect a flame and has safely shut down to prevent unburned gas from building up.
FAIL POINT A High Your boiler appears to have lost all electrical power, meaning it cannot start up or provide any heating or hot water.
FAIL POINT B High Your boiler has lost power or has a serious internal electronic failure, meaning it cannot start the ignition process to provide heating or hot water.
FAIL POINT C High Your boiler has lost power or has a major electrical fault, meaning it cannot provide any heating or hot water despite the fuse board appearing normal.
FAIL POINT D High Your boiler is not reacting when you turn on the heating because it isn't receiving the correct signal to start that specific mode.
FAIL POINT E High Your boiler is not detecting that you have turned on a hot water tap, so it isn't starting the burner to heat the water.
FAIL POINT F High Your boiler is trying to run the heating even though you have turned the control knob to the off position, which usually indicates an internal electronic fault or a stuck component.
FAIL POINT G High Your boiler has shut down because it has detected its internal temperature is too hot and is now in a safety lockout.
FAIL POINT H High Your boiler has failed to light the flame or detects that the flame has gone out, causing the system to shut down for safety.
FAIL POINT I High Your boiler has detected a problem with one of its internal temperature sensors and has stopped working as a safety precaution.
FAIL POINT J High Your boiler has failed to ignite properly, meaning it cannot create the flame needed to provide you with heat or hot water.
FAIL POINT K High Your boiler has encountered a general electrical failure, likely caused by moisture or damage to the internal brain of the unit.

Worcester Bosch 24/28CDi II RSF 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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