Error E385

Safety precautions:

- If you smell gas, leave the property immediately and call the gas emergency number. Do not attempt any electrical or boiler checks if you smell gas.

- Before touching any boiler wiring or opening the boiler, isolate the boiler electrical supply at the fused spur or mains isolator. If you are not competent with electrical work, do not attempt it.

- Do not repeatedly reset the boiler if the same fault returns — that can mask a persistent and potentially dangerous problem and may cause further damage.

Initial checks a homeowner can do:

- Note when the error appears (time of day, when other heavy appliances run, during storms, after power cuts). This helps spot supply dips or patterns.

- Check the boiler fused spur and the consumer unit for tripped breakers or RCDs. Reset any tripped breaker and see if the code returns.

- Check other lights and appliances in the house for signs of low voltage (dimming lights, slow-running motors). If other circuits are affected, the problem is likely the mains supply.

- Ensure the boiler isolator is switched on and the display / power LED on the boiler is lit.

- Try a single reset of the boiler: press and hold the reset button (or turn the selector to R and hold) for 5–10 seconds. Allow the boiler to attempt restart and observe whether the error clears and for how long the boiler runs.

Specific diagnostic and next-step actions:

1) If the error cleared after a reset and does not return, monitor the boiler for several days and log any repeats and circumstances (time, other appliances running, weather). A one-off transient may be safe to monitor.

2) If the error is intermittent or returns, avoid repeated resets. Contact a qualified electrician to measure the incoming mains voltage and check for supply quality. Ask the electrician to measure voltage at the consumer unit and at the boiler supply terminal. The target is to confirm voltage is consistently above the manufacturer threshold (around 195 V) and to check for large voltage drops under load.

3) If the electrician finds mains voltage below acceptable levels or loose/corroded neutral or live connections, they will repair or escalate to the Distribution Network Operator (DNO). Low mains from the street or a defective service cable is the supplier/DNO responsibility.

4) If the electrician confirms the mains supply is healthy and stable, arrange for a Gas Safe registered engineer to inspect the boiler. Tell the engineer you have an E385 low-voltage fault and provide any notes about when it occurs and any unusual noises. The engineer will check the boiler’s internal power supply, transformer, PCB, connectors, and earthing, and will test for failing components (bad capacitors, voltage regulators, relays, or intermittent solder joints) which can cause the same symptom.

5) Do not open the boiler casing or attempt repairs to the PCB, wiring, gas valve, or combustion components yourself. Those tasks must be performed by a Gas Safe engineer and/or a qualified electrician.

When to call urgently:

- If you smell gas, call emergency services/gas emergency immediately.

- If multiple circuits or neighbours show low voltage, contact your electricity supplier/DNO.

- If the boiler locks out repeatedly or makes unusual mechanical noises (grinding, buzzing) that accompany the fault, contact a Gas Safe engineer without delay.

Record keeping and final advice:

- Keep a note of dates/times of faults, the reset attempts, and any electrician/engineer reports. Take photos of the error display and any wiring labels.

- A single transient E385 that clears with a reset may not need immediate repair, but repeated or sustained low-voltage errors require professional diagnostics. Electrical supply faults should be addressed by an electrician/DNO, and internal boiler faults by a Gas Safe registered engineer.