Open 24 hours, 7 days a week  ·  info@jjkgasservices.co.uk ★★★★★ 5.0 on Google · 123 reviews 📞 01942 466 486

Home › Boiler Fault Codes

Boiler Fault Codes Explained
Worcester, Ideal, Baxi & More

Search our complete database of 120+ boiler error codes for Wigan homes. Find out what your fault code means and whether you can fix it yourself or need a Gas Safe boiler repair engineer in Wigan. Used by Wigan homeowners and landlords across Greater Manchester. Call our gas engineer in Wigan on 01942 466 486 if you need a same-day repair.

📞 Call 01942 466 486 Search fault codes ↓

Fault codes covered for all major boiler brands

IDEAL
Ideal
WORCESTERBOSCH
Worcester
BAXI
Baxi
VIESS-MANN
Viessmann
VAILLANT
Vaillant
GLOW-WORM
Glow-worm
POTTER-TON
Potterton
ALPHA
Alpha
FERROLI
Ferroli
MAIN
Main
IDEAL
Ideal
WORCESTERBOSCH
Worcester
BAXI
Baxi
VIESS-MANN
Viessmann
VAILLANT
Vaillant
GLOW-WORM
Glow-worm
POTTER-TON
Potterton
ALPHA
Alpha
FERROLI
Ferroli
MAIN
Main

Error code database

120+ boiler fault codes — all major brands

Use the tabs to browse by brand or search above. DIY Fix codes you may be able to resolve yourself. Engineer codes require a Gas Safe registered engineer.

CodeTypeMeaningWhat to do
EA / 227CheckIgnition failureNo flame detected. Check gas supply is on. Check for frozen condensate pipe in winter. Reset boiler. If persists — call us.
A1 / 229DIY FixLow pressureSystem water pressure too low. Top up via filling key/loop to 1.5 bar. See our pressure guide below.
CE / 207DIY FixLow pressurePressure very low. Top up immediately to 1.5 bar.
H7 / 328DIY FixDry boiler / low pressureRefill system. Top up to 1.5 bar and reset.
E9 / 224EngineerSafety lockout / overheatOverheating in heat exchanger. Pump failure or thermostat issue. Call a Gas Safe engineer.
C6 / 215EngineerFan faultFan speed inconsistent. Blocked flue or fan failure. Engineer required.
D1 / 240EngineerReturn sensor faultReturn NTC sensor damaged or wet. Engineer required.
E2 / 222EngineerFlow sensor faultFlow NTC short circuit. Engineer required.
E5 / 219EngineerReturn sensor open circuitReturn NTC sensor fault. Engineer required.
C0 / 200EngineerFan speed too highCheck mains voltage. Fan or PCB fault. Engineer required.
C2 / 204EngineerFan not spinningMotor seized on startup. Engineer required.
A7 / 360EngineerHot water sensor faultDHW sensor defect. Incorrect hot water temp reading. Engineer required.
A8 / 362EngineerBUS communication errorCommunication error with thermostat or timer. Check wiring or call engineer.
B7 / 257EngineerInternal / PCB errorControl board memory error. PCB replacement likely. Engineer required.
F0 / 238EngineerGas valve faultGas valve check failed. PCB or gas valve fault. Engineer required.
CodeTypeMeaningWhat to do
E119DIY FixLow pressureMost common Baxi fault. Top up pressure to 1.5 bar via filling loop underneath boiler.
E118DIY FixLow pressurePressure gauge too low. Top up system to 1.5 bar.
E117DIY FixHigh pressureSystem over 2.5 bar. Bleed a radiator carefully to lower pressure.
E133CheckGas / ignition failureIgnition failed. Check gas supply is on. Check for frozen condensate pipe in winter. Reset and retry.
E110EngineerOverheat / safety lockoutPrimary circuit overheated. Pump seized or airlock. Engineer required.
E125EngineerCirculation faultWater not circulating. Pump failure or air in system. Engineer required.
E160EngineerFan faultFan speed threshold not reached. Engineer required.
E168EngineerPCB / power faultGhost fault. Power issue or PCB memory error. Engineer required.
E109EngineerPre-check failureSystem has air or pump is stuck. Engineer required.
E20EngineerCH NTC faultCentral heating thermistor faulty. Engineer required.
E28EngineerFlue sensor faultFlue gas sensor fault. Engineer required.
E50EngineerDHW sensor faultHot water sensor short circuit. Engineer required.
E78EngineerGas valve errorGas valve control unit not recognised. Engineer required.
E154EngineerHardware detection faultControl board issue. Engineer required.
E193EngineerAir lockCirculation poor. Air trapped in heat exchanger. Engineer required.
CodeTypeMeaningWhat to do
F1DIY FixLow pressureMost common Ideal fault. Top up pressure to 1.5 bar via filling loop. Reset boiler after topping up.
F2CheckFlame failureBoiler tried to ignite but failed. Check gas supply. Check for frozen condensate pipe. Reset and retry.
F4EngineerReturn NTC faultReturn temperature sensor open circuit or short. Engineer required.
F5EngineerOverheat thermostatHigh limit thermostat has tripped. Possible pump failure or blockage. Engineer required.
F6EngineerFlow NTC faultFlow temperature sensor fault. Engineer required.
F7EngineerDHW sensor faultHot water sensor short circuit. Engineer required.
F9EngineerFan faultFan speed not achieved. Blocked flue or fan motor failure. Engineer required.
L1EngineerOverheat lockoutBoiler has overheated and locked out. Pump or circulation issue. Engineer required.
L2EngineerFlame sensor faultFlame detected when boiler off, or no flame when on. Gas valve or PCB fault. Engineer required.
E119DIY FixLow pressure (some models)Top up pressure to 1.5 bar. Same fix as F1 on older Ideal models.
F3EngineerDHW overtempHot water has overheated. Sensor or valve fault. Engineer required.
F8CheckCondensate faultCondensate pipe blocked or frozen. Thaw external pipe with warm water and reset.
CodeTypeMeaningWhat to do
F22DIY FixLow water pressureMost common Vaillant fault. System pressure too low. Top up via filling loop to 1.5 bar and reset.
F75EngineerPump or pressure sensor faultNo pressure change detected when pump starts. Pump or pressure sensor failure. Engineer required.
F28CheckIgnition failureBoiler failed to ignite. Check gas supply and condensate pipe. Reset and retry. Engineer if persists.
F29CheckFlame extinguishedFlame went out during operation. Check gas supply. Frozen condensate possible in winter. Reset.
F61EngineerGas valve faultGas valve regulation fault. Engineer required immediately.
F62EngineerGas valve faultGas valve delayed closing. Safety shutoff issue. Engineer required.
F63EngineerEEPROM errorPCB memory fault. Control board replacement likely. Engineer required.
F64EngineerSensor short circuitFlow or return NTC short circuit. Engineer required.
F73EngineerPressure sensor faultWater pressure sensor short circuit. Engineer required.
F74EngineerPressure sensor faultWater pressure sensor open circuit or low voltage. Engineer required.
F76EngineerHeat exchanger overheatSafety temperature limiter in primary heat exchanger activated. Engineer required.
F83EngineerFlue temperature faultFlue gas temperature sensor difference detected. Possible flue gas recirculation. Engineer required.
CodeTypeMeaningWhat to do
F0EngineerNo heat request signalControl unit not receiving heat demand. Wiring or PCB fault. Engineer required.
F4CheckFlue gas temperature too highFlue gas overheating. Check flue is clear. Engineer if persists.
F9EngineerFlame failure after ignitionBurner ignited but flame lost. Gas valve or electrode fault. Engineer required.
A1EngineerShort circuit flow sensorFlow temperature sensor short circuit. Engineer required.
A3EngineerShort circuit flue sensorFlue gas temperature sensor short circuit. Engineer required.
A5EngineerShort circuit DHW sensorHot water sensor short circuit. Engineer required.
E1DIY FixLow water pressurePressure too low. Top up to 1.5 bar via filling loop and reset.
E3EngineerSafety temperature exceededBoiler overheated. Pump, thermostat or circulation issue. Engineer required.
E8EngineerFan faultFan speed fault. Blocked flue or fan motor failure. Engineer required.
CodeTypeMeaningWhat to do
F1DIY FixLow water pressurePressure too low. Top up to 1.5 bar and reset boiler.
F9CheckIgnition failureNo flame established. Check gas. Check condensate pipe in winter. Reset and retry.
F23EngineerNTC short circuitTemperature sensor short circuit. Engineer required.
F24EngineerPump overrun faultTemperature rise too fast — pump or blockage. Engineer required.
F25EngineerFlue gas stat faultFlue gas thermostat tripped. Blocked flue or fan issue. Engineer required.
F29CheckFlame extinguishedFlame lost during run. Gas supply issue or condensate. Reset and retry.
F61EngineerGas valve faultGas valve regulation failure. Engineer required immediately.
F75EngineerPressure sensor faultNo pressure change when pump starts. Pump or sensor failure. Engineer required.
CodeTypeMeaningWhat to do
E10DIY FixLow water pressureSystem pressure too low. Top up to 1.5 bar via filling loop.
E01CheckIgnition failureNo ignition detected. Check gas supply and condensate pipe. Reset and retry.
E02EngineerFlame signal faultFlame detected when boiler should be off. Gas valve issue. Engineer required.
E03EngineerOverheatingPrimary circuit overheated. Pump or flow fault. Engineer required.
E04EngineerHigh limit thermostatSafety thermostat activated. Pump failure or blockage. Engineer required.
E05EngineerFlow NTC faultFlow sensor open circuit or short. Engineer required.
E06EngineerReturn NTC faultReturn sensor open circuit or short. Engineer required.
E19EngineerFan faultFan speed not achieved. Flue blockage or fan motor failure. Engineer required.

Most common boiler fault

How to fix low boiler pressure — step by step

Low pressure is the most common boiler fault in UK homes and appears as F1 (Ideal), F22 (Vaillant), E119 (Baxi), A1 (Worcester) and CE (Worcester). Here's how to fix it safely.

1
Turn off your boiler
Switch the boiler off and let it cool completely before touching anything. Never top up a hot boiler.
2
Check the pressure gauge
Find the gauge on the front of your boiler. It should read between 1.0 and 1.5 bar. Green zone is normal. Red zone (low) means you need to top up.
3
Locate the filling loop
Usually a silver braided hose underneath the boiler connecting the CH and cold water pipes. Some Worcester Bosch models use a filling key instead.
4
Top up to 1.5 bar
Slowly open both valves on the filling loop. Watch the gauge carefully. Close both valves immediately when the needle reaches 1.5 bar. Do not overfill.
5
Reset and restart
Once both valves are closed, press and hold the reset button on your boiler for 3–10 seconds. The boiler should start up normally.
6
Still dropping? Call us
If pressure drops repeatedly, there is likely a leak somewhere in the system. This needs a Gas Safe engineer to find and fix the source. JJK Gas Services cover Wigan, Leigh, Horwich, Walkden, Bolton and Salford — call 01942 466 486 or see our boiler repair Wigan page.

Pressure keeps dropping after topping up?

This indicates a system leak — don't keep topping up. Call our Gas Safe engineers in Wigan.

📞 01942 466 486

Why Wigan trusts JJK

Got a fault code? We fix it fast

When a fault code appears, call JJK Gas Services — Wigan's Gas Safe registered boiler repair engineers. £135 callout including first 1.5 hours. Available 24/7.

JJK Gas Services
SG
Boiler Repair, Wigan
★★★★★

He fixed my boiler fault that other companies couldn't diagnose. Professional advice without any upselling. 5-star service and manners.

JJK Gas Services
CH
Weekend Repair, Wigan
★★★★★

Quick response to a combi boiler fault code over a weekend. Found Saturday afternoon, sorted Sunday morning. Great service from start to finish.

JJK Gas Services
MT
Boiler Repair, Wigan
★★★★★

Arrived super quick and got straight to the fault. Fixed it first time. Excellent job and very affordable. Would highly recommend JJK Gas Services in Wigan.

View our boiler repair service →

Common issues

Most common boiler problems in Wigan homes

Based on 17 years of boiler repairs across Wigan, Leigh, Horwich, Walkden and Greater Manchester, these are the faults our Gas Safe engineers see most often.

#1 Most common
Low boiler pressure
F1, F22, E119, A1, CE — accounts for over 40% of all Wigan boiler callouts. Often a DIY fix.
#2 Winter special
Frozen condensate pipe
F8 (Ideal), F28 (Vaillant), EA (Worcester) — extremely common in Wigan winters. Thaw with warm water.
#3 Call an engineer
Ignition failure
EA (Worcester), F2 (Ideal), F28 (Vaillant), E133 (Baxi) — boiler won't light. Usually needs a Gas Safe engineer.
#4 Engineer needed
Pump or fan fault
F75 (Vaillant), C6 (Worcester), E160 (Baxi), F9 (Ideal) — mechanical failure requiring a Gas Safe engineer.

Got a fault code?

Book a diagnosis & repair in Wigan

Your local gas engineer in Wigan · Gas Safe Reg. 939000 · 24/7 emergency cover

Got a fault code you can't fix? Call us now

Gas Safe engineers in Wigan — 24/7 · Same-day response · All brands covered

📞 01942 466 486Boiler repair Wigan