Johnson & Starley E02 Fault Code: Causes, Fixes & Repair Costs
What does the Johnson & Starley E02 fault code mean?
E02 on a Johnson & Starley unit is a false flame lockout: the flame-supervision circuit reported a flame at a moment when no flame should exist — typically before ignition or after the gas valve has closed. Controls treat phantom flame signals as seriously as missing ones, because a flame signal with the valve shut suggests either a supervision fault or, worse, gas burning when it should not be. The usual technical causes are benign: a leaking flame signal from a contaminated or damp electrode, condensate tracking across the electrode or its lead, or a fault in the sensing circuit on the board. The unit locks out and must be professionally checked rather than repeatedly reset.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Contaminated or damp flame electrode Common
Deposits or moisture on the electrode and its insulator leak a small current that reads as flame. Cleaning or replacing the electrode is the most common fix.
- Electrode lead insulation breakdown Sometimes
A degraded HT/sensing lead tracking to earth or chassis creates a phantom signal, often intermittent and damp-weather related.
- Flame-supervision circuit fault on the board Sometimes
The sensing input can fail in a way that self-reports flame; diagnosed once electrode and lead are proven clean and sound.
How to fix it
- Do not keep resetting a false-flame code DIY safe
One reset is acceptable. E02 concerns flame supervision — the safety chain itself — so recurrence should go straight to an engineer.
- Have a Gas Safe registered engineer complete the documented checks Gas Safe engineer
The engineer will inspect and clean or replace the flame electrode and lead, check for condensate ingress around the sensing path, and test the board's flame-supervision circuit. Because this is the flame-safety chain, they should verify correct flame detection and drop-out times before returning the unit to service.
Parts you may need
- Flame sensing electrode and lead · from £30
- Control PCB · from £180
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £100–£300, depending on the underlying cause.
Frequently asked questions
What does E02 mean on my Johnson & Starley?
The controller detected a flame signal when there should be none — a 'false flame'. It is usually a contaminated or damp electrode leaking signal rather than an actual flame, but because it sits in the safety chain the unit locks out and needs an engineer, not repeated resets.
Is a false flame dangerous?
The lockout exists because the condition could indicate gas burning when the valve should be shut. In practice the cause is nearly always electrical leakage on the sensing side — but that distinction is exactly what the engineer verifies. Treat it with respect and, as always, any smell of gas means leave and call 0800 111 999.
What is the usual fix?
Cleaning or replacing the flame electrode and its lead resolves most cases; a board-side supervision fault is the fallback diagnosis. Typical cost £100–£300 depending on which.