The E317 fault code appears on 2 boiler brands — Baxi and Potterton — and on all of them it points to the same kind of problem. The details still differ by brand (thresholds, sub-codes, reset procedure), so use the table below to jump to the page for your boiler.
The brand is printed on the front casing. Tap your brand for the full causes, fixes and repair costs.
| Brand | What E317 means | Severity | DIY? |
|---|---|---|---|
B Baxi | The E317 code appears when your Baxi boiler's PCB detects that the incoming mains electricity is not operating at the expected 50 Hz frequency standard used across the UK grid. Full guide → | Lockout — engineer likely | No |
P Potterton | The E317 code means the boiler's control board has detected that the incoming electrical supply frequency is outside the expected specification. Full guide → | Lockout — engineer likely | No |
The E317 code appears when your Baxi boiler's PCB detects that the incoming mains electricity is not operating at the expected 50 Hz frequency standard used across the UK grid. Rather than continue running under potentially abnormal electrical conditions, the boiler shuts itself down as a precaution. In most cases, either the mains supply has experienced a disturbance, or the PCB itself is misreading an otherwise normal supply — the latter being the more common culprit in practice.
The E317 code means the boiler's control board has detected that the incoming electrical supply frequency is outside the expected specification. In the UK, mains electricity runs at 50 Hz, and the boiler's PCB continuously monitors this. If the frequency drifts significantly or the board itself misreads the supply, the boiler locks out and displays E317 as a safety precaution. This is an electrically-related fault rather than a gas or heating-circuit issue, but it still requires prompt attention — a locked-out boiler will not provide heating or hot water until the underlying cause is resolved.
Causes, fixes & costs for Potterton E317 → · All Potterton codes
Broadly, yes — on Baxi and Potterton the E317 code points to the same class of fault, and the recommended response is similar. Model-specific details such as sub-codes and reset procedures still vary, so follow the page for your own brand.
Not usually. On every brand listed, E317 points to a fault that needs a suitably registered engineer to diagnose and repair. A single reset to rule out a transient glitch is reasonable; repeated resets are not.
For gas boilers, a Gas Safe registered engineer — it is a legal requirement for any work on the appliance. If you smell gas at any point, leave the property and call the National Gas Emergency line on 0800 111 999.
General guidance only — not a substitute for professional advice, and not certified by a registered engineer. Any work on a gas appliance must be carried out by a Gas Safe registered engineer. If you smell gas, call 0800 111 999.
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