Worcester Bosch
Check, then reset onceNo flame detected: the boiler tried to light but failed.
Check the gas is on (hob working, prepay credit) and in freezing weather check the condensate pipe. Then reset once.
Fault code finder
What’s your boiler telling you?
Type the code on your boiler’s display. We’ll tell you what it means, whether it’s safe to try a fix yourself, and when to call a Gas Safe engineer.
Worcester Bosch
Safe to tryWater pressure too low.
Re-pressurise to 1–1.5 bar using the filling loop. If it keeps dropping, there’s a leak.
Worcester Bosch
Check, then reset onceOverheat: the safety thermostat has tripped.
Often low pressure, trapped air or a pump issue. Check the pressure and reset once. If it repeats, call us.
Worcester Bosch
Call an engineerFan fault: no fan speed detected.
Don’t keep resetting. This needs a Gas Safe engineer.
Vaillant
Safe to tryLow water pressure, or dry fire.
Re-pressurise to 1–1.5 bar using the filling loop, then reset.
Vaillant
Check, then reset onceIgnition failed on start-up.
Check the gas supply and condensate pipe, then reset once. If it repeats, call us.
Vaillant
Check, then reset onceFlame lost during operation.
Often a gas supply or flue issue. Check other gas appliances work, then reset once.
Vaillant
Call an engineerPump or pressure sensor fault: no pressure rise detected.
Check the pressure first. If it’s fine and the code returns, the pump or sensor needs an engineer.
Baxi
Safe to tryWater pressure too low.
Re-pressurise to 1–1.5 bar using the filling loop, then reset.
Baxi
Check, then reset onceGas supply interrupted or ignition failure.
Check gas is reaching the boiler (hob, meter, prepay credit) and the condensate pipe isn’t frozen. Reset once.
Baxi
Call an engineerPrimary circulation fault: water isn’t flowing properly.
Check radiator valves are open and pressure is OK. A recurring code usually means a pump issue.
Baxi
Call an engineerFan fault.
This needs a Gas Safe engineer.
Ideal
Safe to tryLow water pressure.
Re-pressurise to 1–1.5 bar using the filling loop.
Ideal
Check, then reset onceFlame loss.
Check the gas supply and a possible frozen condensate pipe, then reset.
Ideal
Call an engineerFan fault.
This needs a Gas Safe engineer.
Ideal
Check, then reset onceIgnition lockout: the boiler failed to light.
Check the gas supply and condensate pipe. Reset once. If it locks out again, call us.
Glow-worm
Safe to tryLow water pressure.
Re-pressurise to 1–1.5 bar using the filling loop, then reset.
Glow-worm
Check, then reset onceIgnition failed on start-up.
Check the gas supply and condensate pipe, then reset once.
Glow-worm
Check, then reset onceFlame lost during operation.
Check other gas appliances work, then reset once. Repeats need an engineer.
Glow-worm
Call an engineerPump or pressure sensor fault.
Check the pressure first. If it returns, call us.
We don’t have that one listed.
Codes vary between models, so check your manual or call our office. We’ll tell you what it means for free.
01204 693 333Safe to tryCheck, then reset onceCall an engineer
Codes and meanings vary between models and years, so always check your boiler’s manual. Only reset a boiler once. If a code comes back, or you smell gas, stop and call a professional. Gas emergency: 0800 111 999.
By brand
Fault codes by manufacturer.
Worcester Bosch fault codes
Greenstar boilers show a two-character code with a three-digit cause code, e.g. EA 227.
4 common codesVaillant fault codes
ecoTEC boilers display an F code on the screen.
4 common codesBaxi fault codes
Baxi boilers show an E code, often with a flashing symbol.
4 common codesIdeal fault codes
Ideal Logic and Vogue boilers show F (fault) and L (lockout) codes.
4 common codesGlow-worm fault codes
Glow-worm boilers share F codes with Vaillant.
4 common codesNo code showing?
Use the Boiler Doctor to diagnose problems by symptom.
Boiler DoctorGet in touch
Code keeps coming back? We’ll fix it.
Fixed £150 call-out including 1.5 hours’ labour. Most repairs are done in one visit.