Potterton E125: no ignition detected on a Promax or Gold
E125 sits in the same family as other manufacturers' ignition-failure codes: gas reached the burner, or was supposed to, and no flame was proved within the attempt window. Older Potterton models in particular benefit from checking gas valve calibration rather than assuming a like-for-like part swap will fix it.
How we read a Potterton E125 fault on site
The check begins outside the appliance with meter credit and supply to other gas appliances, then moves to standing and working pressure at the boiler itself. Electrode condition and spark lead integrity are assessed against Potterton's figures, and where those check out, gas valve output is measured directly rather than adjusted by ear, since incorrect valve calibration produces intermittent ignition failure that looks identical to a worn electrode.
Who should undertake the work
- Gas appliance work must be completed by a suitably qualified Gas Safe engineer
- Oil appliance work should be completed by a suitably qualified OFTEC technician
- Jamie Crawford Heating states both Gas Safe and OFTEC registration
A Potterton E125 fault: engineer's shortlist
- Meter credit and other gas appliances are checked first
- Standing and working pressure are both measured at the boiler
- Electrode gap is compared against Potterton's published spec
- Gas valve output is measured, not adjusted by ear
- Older models sometimes need valve recalibration rather than a swap
Questions we get asked
- Is my boiler too old to repair?
- Age alone does not decide this — parts availability and heat exchanger condition are the deciding factors.
- Could this be an electrical supply issue rather than gas?
- It is checked as part of the process, but ignition failure of this kind is more often gas-side than electrical.
Related help pages
- Noise diagnosisBoiler kettling: the banging and rumbling that means scale
- Glow-worm fault codeGlow-worm F75: pressure sensor and pump communication fault
- Fuel qualitySludge and water in an oil tank: symptoms and remedies
- Alpha fault codeAlpha E1: ignition lockout on an Alpha combi boiler
- Potterton rangePotterton Promax: a long-standing value combi range
- Older system layoutsVented gravity-fed systems: how older heating layouts work
Services that cover this
Where we deal with this
Sorted quickly: a Potterton E125 fault
Where this leaves you: E125 rewards checking the gas side properly before any part is fitted — pressure and valve calibration first, always.
Use the enquiry form to describe the appliance, fault code and what changed before the problem started.
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