Remeha E43 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha E43 fault code mean?
The E43 fault code on a Remeha boiler signals that one or more internal automation parameters have moved outside the range the boiler's control system is programmed to accept. In plain terms, the boiler's brain has detected that a setting or operating value is out of bounds and has locked the boiler out as a precaution. This prevents potential damage to components and keeps the household safe. The fault is most commonly linked to a corrupted or incorrectly configured parameter set rather than a failed mechanical part, so a reset — or a quick engineer visit to re-programme the settings — is often all that is needed.
General guidance only — not a substitute for professional advice, and not certified by a Gas Safe engineer. Always have your specific appliance assessed by a qualified professional. Any gas work must be carried out by a Gas Safe registered engineer. If you smell gas or suspect carbon monoxide, leave the property and call the National Gas Emergency line on 0800 111 999.
Common causes
- Power cut or voltage spike corrupting stored settings Common
A sudden loss of mains power or a voltage surge can scramble the parameter values held in the boiler's control board memory. When the boiler restarts and checks those values, it finds them outside acceptable limits and triggers E43.
- Incorrect parameter programming Common
If a setting was entered incorrectly during installation, commissioning, or a recent service — perhaps the wrong system type was selected or a configuration menu was changed inadvertently — the boiler may flag E43 the next time it performs a self-check.
- PCB or control board fault causing parameter drift Sometimes
A failing or partially faulty printed circuit board can cause the stored parameter values to drift over time without any external trigger. If the board is unable to reliably hold or read its own settings, E43 will recur even after the parameters are corrected.
- Firmware or software glitch Rare
In rare cases, a software error within the boiler's operating firmware can cause the control system to misread valid parameters as out-of-range. This is unusual but can occur on older boards that have never had a firmware update.
How to fix it
- Check for an obvious external cause first DIY safe
Before doing anything else, think back over the past 24–48 hours. Was there a power cut, a blown fuse, or any electrical work in the property? This context is useful both for deciding whether a reset is likely to work and for telling the engineer if one is needed.
- Reset the boiler DIY safe
Consult your Remeha boiler manual for the exact reset procedure for your model — it typically involves pressing and holding the reset button for a few seconds until the display clears. Attempt the reset up to two or three times. If the E43 code clears and the boiler fires up normally, monitor it over the next day or so to confirm it stays running. Do not reset more than three times, as repeated lockouts without resolution can mask a deeper fault.
- Check that the gas and electricity supplies are normal DIY safe
Confirm the gas isolation valve on the supply pipe to the boiler is fully open (handle in line with the pipe), check that no other gas appliances in the home have lost supply, and ensure the boiler's electrical supply hasn't tripped at the consumer unit. Rectify any obvious supply issues before attempting another reset.
- Call a Gas Safe registered engineer if the fault returns Gas Safe engineer
If E43 reappears after resetting, the parameters need to be inspected and corrected by a qualified professional. The engineer will access the boiler's configuration menu, check each parameter against the commissioning data for your installation, and restore any values that are out of range. If the board itself is suspected of causing the drift, the engineer will also test and — if necessary — replace the PCB.
Parts you may need
- Printed circuit board (PCB / control board) · from £220
- Programmer / controller unit · from £85
The exact spare depends on your boiler's GC number (on the data badge). Check this against the part before buying.
Typical repair cost
Expect to pay roughly £100–£320, depending on the underlying cause.
Frequently asked questions
Can I fix Remeha E43 myself without an engineer?
You can safely try a boiler reset yourself — that resolves E43 in a good number of cases, particularly when the fault followed a power cut. Beyond the reset, though, the fix involves accessing the boiler's parameter configuration menus, which requires specialist knowledge and tools. If the reset does not clear the code, you will need a Gas Safe registered engineer to investigate and correct the settings.
How much does it cost to fix Remeha E43 in the UK?
If the fault is purely a parameter programming issue, expect to pay roughly £100–£200, which typically covers the engineer's call-out and the time spent accessing and correcting the settings. If the control board itself has failed and needs replacing, costs generally rise to around £280–£320 once parts and labour are included. PCB replacement on certain Remeha models can occasionally push beyond this range, so it is worth asking the engineer for a written quote before authorising the work.
Why does E43 keep coming back after I reset it?
A recurring E43 suggests something is actively causing the parameters to go out of range rather than it being a one-off glitch. The most likely culprits are an intermittently failing PCB that cannot reliably retain its settings, or a wiring issue causing the control board to receive corrupted data. An engineer will need to carry out a thorough diagnostic — including checking board voltages and connections — to find the root cause and prevent the fault from returning.
My Remeha boiler is over 10 years old and showing E43 — is it worth repairing?
Remeha boilers typically have a service life of around 10–15 years with regular maintenance. If your boiler is within that range and the repair is limited to re-programming or a minor component swap, repair is usually the more economical choice. However, if the PCB has failed on an older boiler and the engineer also identifies worn ancillary parts, it may make more financial sense to replace the boiler rather than spend several hundred pounds keeping an ageing unit running. Ask your engineer for an honest assessment before committing to a costly repair.