Verified boiler fault code
Potterton E118 Fault Code (Assure Combi & System)
Water pressure is low, below 0.5 bar.
Safety disclaimer
Fault code summary
- Manufacturer
- Potterton
- Fault code
- E118
- Fault type
- Low pressure, Pressure sensor
- Severity
- lockout
- Reset
- Not specified
- Applicable models
- Potterton Assure Combi, Potterton Assure System
Quick answer
Water pressure is low, below 0.5 bar.
What does this fault code mean?
Water pressure is low, below 0.5 bar.
Common causes
- Water pressure below 0.5 bar.
Symptoms
- The boiler displays E118 and heating may stop.
What can the homeowner safely check?
- Read the pressure gauge/display without removing the casing.
Boiler reset information
Reset information was not provided in the verified manufacturer source. Do not repeatedly reset an unresolved fault.
When should I call an engineer?
Contact a suitably qualified heating engineer when the fault persists, the boiler locks out, or the manufacturer instructions do not resolve it. For gas appliance work in the UK, use a Gas Safe registered engineer.
Engineer diagnosis
- Check system pressure, pressure sensing and possible system loss.
Applicable boiler models
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Manufacturer documentation
Boiler Error Codes | BaxiPotterton Assure Combi & System — E118: Water pressure LOW (<0.5 bar).
Last verified
2026-09-12
Frequently asked questions
What does Potterton E118 mean?
Water pressure is low, below 0.5 bar.