Error E317

Safety precautions:

1. If you smell gas, do not touch the boiler; evacuate the property and call the gas emergency number and a Gas Safe engineer. 2. Turn off the electricity to the boiler at the isolator before doing any checks that require accessing internal parts. 3. Do not attempt gas or sealed-combustion system repairs unless you are a Gas Safe registered engineer. 4. Do not repeatedly reset the boiler — that can cause further damage.

Initial homeowner checks you can safely do:

1. Note the exact error code and any other codes or LEDs shown on the display. 2. Check the system pressure on the boiler pressure gauge — aim for approximately 1.0–1.5 bar when cold for most domestic systems. 3. Look for visible leaks around the boiler, pipes, radiators or valves. 4. Check that all radiator valves and the boiler flow/return isolation valves are open. 5. If you use a generator or inverter, confirm household supply is stable and normal (mains frequency in the UK should be ~50 Hz). If you suspect the mains frequency is wrong or you are on a temporary generator supply, stop using the boiler and call an electrician/engineer.

Diagnostic and basic fix steps you can try safely:

1. If low pressure (below ~0.7–1.0 bar): repressurise the system using the filling loop according to your boiler handbook (open the filling loop valves until pressure reaches about 1–1.5 bar, then close). If you are not confident locating or operating the filling loop, stop and call an engineer. 2. After topping up, bleed any trapped air from radiators to improve circulation. 3. Turn the boiler off for a minute, then use the manufacturer reset procedure (press and hold the reset button or turn the selector to R for 5–10 seconds as per your model). Wait for the boiler to attempt restart. 4. If the code clears and the boiler runs normally, monitor pressure and performance. If pressure drops again or the fault returns, do not keep running the boiler — arrange an engineer visit. 5. If pressure was normal, check for pump operation noises or vibration (pump should run when the boiler calls for CH). If the pump appears dead or blocked (no sound) the pump or wiring may be faulty. 6. If you suspect incorrect mains frequency or unstable supply (for example you recently switched to generator/inverter power), stop using the boiler and contact a qualified electrician — running the boiler on incorrect Hz can cause control/PCB faults.

When to call a professional and what they will check:

1. Call a Gas Safe registered heating engineer if the fault persists after basic checks and reset, if you cannot restore/maintain correct system pressure, if there are visible leaks, or if the pump, flow sensor, pressure sensor, or PCB may be faulty. 2. The engineer will check system pressure and leak history, verify pump operation and isolation valves, test the flow and return thermistors/NTC sensors, inspect the pressure/flow switches, check for blocked heat exchanger or flow restrictions, and test the PCB and mains supply quality. 3. If a wrong frequency or unstable mains supply is suspected, an electrician or power-supply specialist should verify the mains waveform and frequency before the engineer replaces electronic parts.

Final notes:

- E317 indicates a condition that should not be ignored — addressing the root cause (low pressure, poor circulation, pump or sensor failure, or abnormal power supply) is important to avoid damage. - Do not attempt gas-side repairs yourself. If in doubt, switch the boiler off and arrange a Gas Safe engineer visit.