Potterton Boiler Fault Codes Explained
Potterton fault codes tell you which part of the boiler has a problem — but they don't tell you how to fix it safely. Here's what each common Promax, Assure, Gold and Titanium code means, what you can check yourself, and when to call a Gas Safe engineer.
E119 Fault
Low system water pressure — water pressure switch hasn't operated, boiler locked out.
E125 Fault
Primary circuit circulation fault — boiler can't confirm water is circulating, often pump or airlock.
E133 Fault
Ignition fault — boiler couldn't establish a flame. Often frozen condensate or gas supply.
E160 Fault
Fan or fan wiring fault — boiler can't confirm flue gases are being safely expelled, locks out before lighting.
When to call a Gas Safe engineer
Any work inside the boiler casing — replacing the fan, pump, igniter, flame electrode, gas valve, pressure switch or PCB — is gas work that must be done by a Gas Safe Registered engineer. The safe checks on each fault-code page are limited to what you can do without opening the boiler.
If you can smell gas, turn off the gas at the meter, open windows, don't use switches, and call the National Gas Emergency Service on 0800 111 999 immediately.