Common problems guide

The most common Johnson Starley boiler problems

The faults we see most often across the Johnson Starley range — with plain-English causes, what to check first, estimated repair costs, and whether it's a DIY job or needs a Gas Safe engineer. Based on fault-code data across 11 Johnson Starley boiler models.

94 unique codes
11 models covered
8 DIY-safe (top 8)
8 engineer needed

The most common Johnson Starley faults

01
E01 High DIY-safe

Your boiler has tried to light several times but has been unable to create a flame, meaning you will not have any heating or hot water.

What to try first

Check if other gas appliances in your home, such as a gas hob, are working correctly to ensure gas is reaching the property.Verify that your gas pre-payment meter (if applicable) has sufficient credit.Try resetting the boiler by following the instructions in your user manual to clear the fault.

Est. cost
£120-£350
Parts
Ignition Electrode, Gas Valve, Flame Sensing Probe
Full guide for J32 System ET E01
02
E03 High DIY-safe

Your boiler has shut down because it has detected it is getting too hot, which is a safety feature to prevent damage.

What to try first

Check that all radiator valves are fully open to allow water to flow.Ensure there are no blockages in the system by checking if any external pumps are running.Try resetting the boiler via the control panel once it has cooled down.

Est. cost
£120-280
Parts
Overheat Thermostat, Circulation Pump, Temperature Sensor (NTC)
Full guide for J32 System ET E03
03
F37 High DIY-safe

Your boiler has stopped working because the water pressure in the central heating system has dropped too low.

What to try first

Locate the metal braided filling loop underneath or near your boiler.Slowly open the one or two valves on the loop until you hear water flowing.Watch the pressure gauge until it reaches between 1.0 and 1.5 bar, then close the valves tightly.

Est. cost
£0-160
Parts
Filling loop, Expansion vessel, Pressure sensor
Full guide for J32 System ET F37
04
F40 High DIY-safe

Your boiler has detected that the water pressure in the central heating system is too low or too high for it to operate safely.

What to try first

Check the pressure gauge on the front of the boiler or under the casing; it should be between 1.0 and 1.5 bar.If it is below 1.0, use the external filling loop valves to top up the system until the needle reaches the green zone.If the pressure is too high, bleed a radiator to release water and lower the pressure.

Est. cost
£0-160
Parts
Filling loop, Expansion vessel, Pressure sensor
Full guide for J32 System ET F40
05
IGNITION LOCKOUT High DIY-safe

Your boiler has failed to light after several attempts and has locked itself for safety, leaving you without heating.

What to try first

Check that your gas pre-payment meter (if applicable) has credit.Ensure other gas appliances in your home, such as a hob, are working correctly.Press and hold the reset button for five seconds to attempt a restart.

Est. cost
£120-350
Parts
Ignition electrode, Gas valve, Spark generator
Full guide for J32 System ET IGNITION LOCKOUT
06
OVERHEAT LOCKOUT High DIY-safe

Your boiler has switched itself off because it became too hot, acting as a safety measure to protect the internal components.

What to try first

Wait at least 15 minutes for the unit to cool down completely.Check that all internal registers and warm air vents are open and not blocked by furniture.Press the 'Reset' button on the control panel to see if the heater restarts.

Est. cost
£120-280
Parts
Overheat Thermostat, Circulating Fan Motor, Limit Switch
Full guide for J32 System ET OVERHEAT LOCKOUT
07
EEPROM LOCKOUT High DIY-safe

Your boiler's computer memory has encountered a software error and can no longer process instructions safely.

What to try first

Locate the main power switch for the boiler (usually a fused spur nearby).Turn the power off for at least 30 seconds.Turn the power back on and wait for the boiler to complete its startup sequence.

Est. cost
£280-450
Parts
Main Control PCB, Display Interface Module
Full guide for J32 System ET EEPROM LOCKOUT
08
REMOTE RESET LOCKOUT High DIY-safe

Your heater has encountered a temporary electronic error and needs a manual reboot to resume operation.

What to try first

Locate the mains power switch for your heating system (usually a fused spur near the unit).Turn the power switch to the 'OFF' position and wait for 30 seconds.Switch the power back to 'ON' and check if the lockout cleared.

Est. cost
£0-120
Parts
Electronic Control Board, Reset Switch
Full guide for J32 System ET REMOTE RESET LOCKOUT

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