Error E317

Safety first: if you smell gas, evacuate immediately and call the emergency gas number. If you are unsure about any electrical work, do not attempt it — contact a qualified electrician. Do not open the boiler or attempt internal electrical repairs unless you are a Gas Safe‑registered engineer and competent with live electrical work.

Initial homeowner checks:

1. Check other electrical appliances in the house to confirm mains power is present and normal (lights, cooker, fridge). Note whether anything else is abnormal.

2. Check the boiler display and any other error or warning lights. Write down the full code and any sequence of flashing lights.

3. Check the consumer unit/fuse box for tripped breakers or blown fuses and reset if safe to do so.

4. If you have a prepay electricity meter, ensure it has credit and is actually supplying power.

5. If the property is on a temporary generator, inverter or backup supply (including certain off-grid systems or some UPS devices), confirm whether that supply is designed to produce a steady 50 Hz output — many portable generators and some inverters can have unstable frequency and voltage.

Basic restart attempt (safe, homeowner-level):

1. Turn off the boiler using the normal control or the isolator switch. Wait 30 seconds.

2. Turn the boiler back on and attempt a reset using the boiler’s reset button (hold for 3–10 seconds as per the boiler instructions).

3. Watch the display. If the E317 returns immediately or after restart attempts, do not keep resetting repeatedly — repeated resets can cause further issues.

If the initial checks and reset do not clear the fault:

1. Contact your electricity supplier or a qualified electrician to check the incoming supply frequency and voltage. Ask them to measure mains frequency; acceptable should be around 50 Hz for UK supply. Do not attempt to measure mains yourself unless you are a trained electrician.

2. If you are using a generator/inverter/UPS, try connecting the boiler to a known-good mains supply (if available) or have the generator/inverter checked for proper frequency/voltage output. The fault often clears when the boiler receives a stable correct-frequency supply.

3. If the mains supply is normal, the issue is likely internal (PCB or frequency sensing). Do not open the boiler further. Contact a Gas Safe registered engineer and explain the E317 frequency error and the supply checks you have already done. A Gas Safe engineer will inspect the boiler electronics, wiring and may arrange for a replacement control board or repairs if the frequency sensor or PCB is faulty.

When to call professionals and who to call:

- Call an electrician or your power supplier if there are signs of abnormal mains supply, tripped breakers you cannot reset safely, or if you rely on a generator/inverter.

- Call a Gas Safe registered heating engineer if the mains frequency is confirmed OK but the boiler still shows E317, or if the engineer needs to access internal boiler electronics.

Final notes: E317 usually means a supply-frequency or detection problem rather than a user-serviceable fault. Do not continue to use the boiler while the fault persists, and avoid attempting internal electrical repairs yourself. If in doubt, get a Gas Safe engineer and/or a qualified electrician to inspect and fix the problem.