BoilerFaultCodes 0.0
This code is simply a reminder of the last error your boiler experienced and does not necessarily mean there is an active problem right now.
Worcester Bosch Greenstar 30HE Fault codes & diagnostics
19 fault codes with plain-English explanations, severity ratings, DIY guidance, and repair cost estimates.
Combi Natural GasLPG 30 kW 2003-2007 Discontinued
GC Number 47-311-56
Replaced by: Greenstar 30i
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. 1 Emergency
14 High
1 Medium
3 Low
Just want the most common Worcester Bosch Greenstar 30HE faults?
The top 6 problems in plain English — with causes, DIY checks and repair costs.
Fault codes
All 19 documented codes
Tap any card for details
A1 Your boiler has detected that there is not enough water circulating through the system to operate safely.
Your boiler has detected that there is not enough water circulating through the system to operate safely.
What to check first
- Check your boiler's pressure gauge to see if it is below 1 bar
- Locate the filling loop (usually silver braided hoses under the boiler)
- Slowly open the valves until the pressure reaches 1.5 bar, then close them tightly
Parts commonly replaced
- Filling loop
- Expansion vessel recharge
- Internal pump
Related codes
A7 Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps will only run cold or slightly warm.
Your boiler is struggling to accurately measure the temperature of your hot water, which usually means your taps will only run cold or slightly warm.
Parts commonly replaced
- Domestic Hot Water (DHW) NTC Sensor
- Connecting Wiring Harness
Related codes
A8 Your boiler's internal computer has lost its connection with the main control board, preventing the system from operating.
Your boiler's internal computer has lost its connection with the main control board, preventing the system from operating.
Parts commonly replaced
- Wiring harness
- Heatronic PCB
- User Interface Control board
Related codes
AC Your boiler's main control computer is unable to communicate with its internal plug-in components, meaning the system cannot safely start up.
Your boiler's main control computer is unable to communicate with its internal plug-in components, meaning the system cannot safely start up.
Parts commonly replaced
- PCB (Printed Circuit Board)
- Heatronic Module
- Internal Wiring Harness
Related codes
Ad Your boiler is unable to detect the temperature sensor for your hot water tank, which means it doesn't know when to heat your water.
Your boiler is unable to detect the temperature sensor for your hot water tank, which means it doesn't know when to heat your water.
Parts commonly replaced
- Cylinder NTC sensor
- Sensor wiring harness
Related codes
b1 Your boiler's internal computer is having trouble communicating with its identity chip, meaning it doesn't recognize its own settings.
Your boiler's internal computer is having trouble communicating with its identity chip, meaning it doesn't recognize its own settings.
Parts commonly replaced
- Code plug
- Printed Circuit Board (PCB)
C1 Your boiler has stopped working because the internal fan, which clears exhaust gases, isn't spinning fast enough to operate safely.
Your boiler has stopped working because the internal fan, which clears exhaust gases, isn't spinning fast enough to operate safely.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
- Venturi tube
Related codes
C4 Your boiler's fan is running constantly or at the wrong time, which is usually caused by a safety component failing to tell the fan when to stop.
Your boiler's fan is running constantly or at the wrong time, which is usually caused by a safety component failing to tell the fan when to stop.
Parts commonly replaced
- Air pressure switch
- Main PCB (Printed Circuit Board)
- Fan assembly
Related codes
C6 Your boiler's fan is spinning faster than it should, which has caused the system to shut down for safety purposes.
Your boiler's fan is spinning faster than it should, which has caused the system to shut down for safety purposes.
Parts commonly replaced
- Fan assembly
- Printed Circuit Board (PCB)
Related codes
E2 Your boiler has detected a faulty internal temperature sensor, which means it cannot accurately measure how hot the water is and has stopped running for safety.
Your boiler has detected a faulty internal temperature sensor, which means it cannot accurately measure how hot the water is and has stopped running for safety.
Parts commonly replaced
- Central Heating Flow NTC Sensor
- Wiring Harness Connection
Related codes
E9 Your boiler has switched itself off because it has detected that it is getting far too hot inside.
Your boiler has switched itself off because it has detected that it is getting far too hot inside.
What to check first
- Check that the boiler pressure is between 1 and 1.5 bar on the needle gauge.
- Ensure all radiator valves are fully open to allow water to flow.
- Press the 'Reset' button on the front of the boiler once the system has cooled down.
Parts commonly replaced
- Overheat Thermostat
- Central Heating Pump
- Heat Exchanger
EA Your boiler is failing to light the gas or isn't detecting that the flame has started, causing the system to shut down for safety.
Your boiler is failing to light the gas or isn't detecting that the flame has started, causing the system to shut down for safety.
What to check first
- Check if other gas appliances in your home, like a hob, are working to confirm your gas supply is active.
- If it is freezing outside, check that your external condensate pipe hasn't frozen and blocked.
- Press and hold the reset button for five seconds to see if the boiler restarts.
Parts commonly replaced
- Ignition Electrode
- Flame Sensor (Ionisation Probe)
- Gas Valve
- PCB
Related codes
F0 Your boiler's internal computer has encountered a communication error or software glitch that is preventing it from running safely.
Your boiler's internal computer has encountered a communication error or software glitch that is preventing it from running safely.
What to check first
- Press and hold the reset button for five seconds
- Wait for the boiler to complete its restart sequence
- If the code persists, turn the main power switch to the boiler off and back on again
Parts commonly replaced
- Main Printed Circuit Board (PCB)
- Wiring harness
Related codes
F7 Your boiler is still sensing a flame even when it should be turned off, which is a safety conflict that prevents the system from starting.
Your boiler is still sensing a flame even when it should be turned off, which is a safety conflict that prevents the system from starting.
Parts commonly replaced
- Ionisation Probe
- Flame Sensing Electrode
- Printed Circuit Board (PCB)
Related codes
FA Your boiler is still detecting a flame even after it should have turned off, which is a safety concern that prevents the system from running.
Your boiler is still detecting a flame even after it should have turned off, which is a safety concern that prevents the system from running.
Parts commonly replaced
- Gas valve
- Ionisation probe
- Control board (PCB)
Related codes
FC Your boiler's main control board is having trouble communicating with the display panel, meaning the system cannot correctly send or receive instructions.
Your boiler's main control board is having trouble communicating with the display panel, meaning the system cannot correctly send or receive instructions.
Parts commonly replaced
- Main PCB
- Display Interface Board
- Wiring Harness
Related codes
Fd Your boiler has been put into a temporary reset mode because the button was held down too long or pressed accidentally.
Your boiler has been put into a temporary reset mode because the button was held down too long or pressed accidentally.
What to check first
- Press the reset button firmly once and release it immediately
- Wait up to 30 seconds for the display to return to a normal temperature reading
- If the code persists, switch the boiler's power off and back on at the fused spur switch
Related codes
P1, P2, P3, P1... Your boiler is simply starting up and checking its internal systems as part of a normal restart process.
Your boiler is simply starting up and checking its internal systems as part of a normal restart process.
What to check first
- Wait 5-10 minutes for the sequence to complete
- Ensure the gas and power supply are turned on
- Check if the reset button was pressed accidentally
Status & diagnostic codes 1 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.
1 operating states & engineer diagnostics
Not faults — these are normal operating states. Tap to expand.