If your Baxi boiler is showing E385 or 165, Baxi’s current error-code table describes it as under voltage. The boiler has detected that the electrical supply reaching it is below the level its controls expect.
This is an electrical-supply code, not a gas-pressure or heating-water-pressure warning. The display tells you what the boiler has detected, but it does not identify exactly where the low-voltage condition originates.
What does Baxi E385 / 165 mean?
Domestic boilers use mains electricity to run their controls, pump, fan, valves and safety systems. Those components need a suitable supply. E385 / 165 appears when an applicable Baxi boiler detects under-voltage.
Under-voltage simply means the measured voltage is too low for normal operation. The boiler may stop or protect itself rather than continue with an unsuitable supply.
Baxi lists E385 / 165 separately from E317 / 162. E385 / 165 means under-voltage, while E317 / 162 means the electrical supply frequency is wrong. The codes are both supply-related, but they are not interchangeable.
Which Baxi boilers can show E385 / 165?
Baxi’s current grouped error-code table includes E385 / 165 for ranges such as Platinum Compact, Duo-tec Compact, Megaflo Compact System, Baxi 600 and 800 Combi and System, Duo-tec Combi, Assure Combi and System, Platinum and Platinum+, Megaflo System, and EcoBlue Combi and System boilers.
Baxi has used different controls and code systems across its boiler generations. Confirm the model from the front of the closed appliance or its paperwork, then use the user guide written for that exact boiler. Do not assume a similar-looking code on another model has the same meaning.
What might you notice?
The boiler may stop providing heating or hot water, display E385 and 165 in sequence, or return to normal after a brief interruption before showing the code again. You might also have noticed lights dimming, appliances restarting or a power cut elsewhere in the home.
Those observations are useful, but none proves the cause. A problem may affect the wider electricity network, the property’s electrical installation, the boiler’s dedicated supply or the appliance itself. Suitable electrical testing is needed to separate those possibilities.
Safe checks for a homeowner
Keep the boiler casing closed. You can safely record what is happening without touching wiring or internal components:
- Photograph the full display, including any other symbol or alternating number.
- Write down the exact Baxi model.
- Note whether there was a recent power cut, flicker or other electrical disruption.
- Check whether lights and other household appliances are behaving normally.
- Ask a neighbour whether they have a supply problem only if it is practical and safe.
- Check the exact user guide for any ordinary reset permitted for your model.
If the manual permits a homeowner reset, try it once after the wider supply appears stable. If E385 / 165 remains or returns, stop resetting and arrange professional help.
Do not open the boiler, remove an electrical cover, test voltage, inspect terminals, replace a fuse repeatedly, work at the consumer unit or use a meter on boiler wiring. Do not order a circuit board or another part solely from the code.
Could this be a power-network problem?
It could be, particularly if several properties or several appliances are affected together. In Great Britain, dialling 105 connects you to the local electricity network operator for power cuts and electricity-network emergencies.
If only the boiler is affected, the issue still needs a competent check. Tell the attending engineer or electrician whether the fault followed an outage, whether lights dimmed and whether the code clears when the rest of the home appears normal.
When is urgent electrical help needed?
Keep away from equipment that is hot, buzzing, sparking, scorched or visibly damaged. If you smell burning or see smoke, leave the affected area, call the emergency services when necessary and do not touch damaged switches or cables.
If anyone receives an electric shock, do not touch them while they may still be in contact with the electrical source. Call 999 and follow the emergency operator’s instructions.
If you smell gas, suspect carbon monoxide or a carbon-monoxide alarm sounds, do not operate electrical switches or use naked flames. Leave the property and call the National Gas Emergency Service on 0800 111 999 from a safe place.
Will a reset fix Baxi E385 / 165?
A reset may clear the display after a very brief supply disturbance, but it does not repair low voltage or an appliance fault. Repeatedly resetting the boiler can hide the pattern without making the electrical supply suitable.
If the code returns, photograph it and leave the boiler closed. The repair visit should establish why the boiler is detecting under-voltage and fix the confirmed fault safely.
What information helps the engineer?
Have the model, display photo and timing ready. Note whether heating, hot water or both stopped, whether other appliances were affected and whether the problem followed electrical work or a power cut. Do not recreate the fault to collect more information.
For more homeowner-safe guidance, browse our boiler help and advice.
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Baxi E385 / 165: quick answers
What does Baxi fault code E385 / 165 mean?
It means the boiler has detected under-voltage: the electrical supply reaching it is below the level expected by its controls.
Is Baxi E385 / 165 the same as E317 / 162?
No. E385 / 165 means under-voltage. E317 / 162 refers to the electrical supply frequency.
Can a power cut cause E385 / 165?
A supply disturbance may coincide with the code, but the display does not prove the cause. Note whether other appliances were affected and arrange a repair if the code persists or returns.
Can I fix Baxi E385 / 165 myself?
Do not test voltage or open the boiler. You can record the display, check the correct user guide and try one normal reset only if that guide permits it.