Worcester Bosch Boiler Error Codes: Full UK Guide (2025)
All Worcester Bosch boiler fault codes explained ā causes, fixes, UK repair costs, and when to call a Gas Safe engineer.
Worcester Bosch Boiler Error Codes: Full UK Guide (2025)
Worcester Bosch boilers are some of the most reliable in the UK ā but like any heating system, they can display error codes when something isn't working correctly. This guide explains every major Worcester Bosch error code, what it means, how to fix it, and typical repair costs across the UK.
This guide is written for homeowners in London, Manchester, Birmingham, Leeds, Glasgow, Liverpool, Bristol and everywhere else in the UK.
Need emergency help? Visit our Boiler Cover or book a Boiler Service.
EA Error Codes (Ignition / Flame Problems)
EA 227 ā Ignition Failure
Meaning: The boiler cannot ignite.
Causes:
- Faulty ignition electrode
- Blocked condensate pipe (common in freezing UK winters)
- No gas supply
- Frozen external pipework
Fix:
- Reset boiler
- Thaw frozen pipes
- Check gas supply
- Engineer: replace electrode or gas valve
Typical Repair Cost (UK): Ā£90āĀ£250
EA 229 ā Flame Not Detected
Meaning: Boiler ignites but cannot detect flame.
Common in: Older Worcester 24CDi, 28CDi, Greenstar i.
Fix: Engineer must check: flame sensor, PCB, gas valve.
Cost: Ā£120āĀ£350
A Series Errors (Temperature & Sensor Faults)
A21 ā Flow Temperature Sensor Fault
Meaning: The flow temperature is reading too high or too low.
Fix: Sensor needs recalibration or replacement.
Cost: Ā£80āĀ£180
A28 ā Return Temperature Sensor Fault
Meaning: Temperature difference too high.
Fix: Bleed radiators, check pump.
Cost: Ā£90āĀ£160
E Series Errors (Overheating & Serious Faults)
E9 ā Overheat or Heat Exchanger Blockage
Risk level: High
Causes:
- Pump failure
- Blocked heat exchanger
- Airlock in system
Fix: Must be checked by a Gas Safe engineer.
Cost: Ā£150āĀ£450
H Series Errors
H07 ā Low System Pressure
Meaning: Water pressure below 1.0 bar.
Fix: Top up using filling loop.
If pressure drops again ā leak likely.
Cost: Ā£0 (self fix) to Ā£180 for leak tracing.
CE / C Errors (Communication & Control Faults)
CE 207 ā Communication Error
Meaning: PCB cannot communicate with control unit.
Fix: Engineer repair ā likely PCB.
Cost: Ā£200āĀ£450
C6 ā Fan Speed Fault
Meaning: Fan cannot reach correct speed.
Fix: Fan replacement.
Cost: Ā£180āĀ£350
Lockout Codes
L2 ā Flame Loss / Lockout
Meaning: Boiler tried to fire but failed.
Fix: Reset boiler ā If recurring, engineer needed.
Cost: Ā£120āĀ£250
When to Call a Gas Safe Engineer
You must NOT attempt repairs if the issue involves:
- Gas valve
- PCB
- Burners
- Ignition electrodes
- Flues
- Internal components
If unsure, book a professional:
Typical Worcester Bosch Repair Costs (UK 2025)
| Fault Type | Typical Cost |
|---|---|
| Ignition faults | Ā£120āĀ£250 |
| Pressure faults | Ā£80āĀ£150 |
| PCB replacement | Ā£250āĀ£450 |
| Fan replacement | Ā£200āĀ£350 |
| Heat exchanger | Ā£400āĀ£700 |
| Annual boiler service | Ā£70āĀ£90 |
These are average UK prices ā London tends to be 10ā15% higher, while the North West and Midlands are typically cheaper.
Final Advice
Worcester Bosch error codes are often straightforward ā but repeated faults signal a deeper problem. If your boiler is older than 10ā12 years, breakdowns become more common.
Stay protected with:
These prevent expensive emergencies and ensure a safe, reliable boiler all year round.