Remeha E45 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha E45 fault code mean?
The E45 code appears on Remeha boilers when the internal control unit (PCB) has lost its programmed settings and fallen back to factory default parameters. In this state the boiler can no longer run correctly, so it locks out and displays E45 to alert you that the brain of the appliance needs attention. The fault can arise either because the PCB itself has suffered a hardware failure, or because the settings stored on it have become corrupted – both outcomes lead to the same lockout. This is not a fault you can clear with a simple reset; the underlying control unit issue must be resolved first.
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
- Failed or faulty PCB (control unit) Common
The most common cause. The PCB has developed a hardware fault – often caused by a power surge, moisture ingress, or age-related component degradation – and can no longer retain or execute its operating parameters. A failed PCB almost always requires a direct replacement rather than a repair.
- Corrupted parameter settings Sometimes
In some cases the PCB itself is still functional, but the configuration data it holds has become corrupted, for example after a power outage or an incomplete firmware update. A Gas Safe engineer with Remeha diagnostic equipment may be able to reprogram the correct values without replacing the entire board.
- Wiring or connection fault to the control unit Sometimes
Loose, corroded, or damaged wiring harnesses feeding the control unit can cause intermittent data errors that the boiler interprets as a parameter fault. An engineer will check all connections before condemning the PCB.
How to fix it
- Note down the fault code before doing anything else DIY safe
Before switching the boiler off, make a note of E45 (and anything else shown on the display). This gives the engineer the full picture when they arrive and prevents important diagnostic information being lost.
- Switch the boiler off at the programmer or controls DIY safe
Turn the boiler off using the controls on the unit or the programmer – do not isolate power unless instructed otherwise. There is no benefit to repeatedly resetting an E45, as it will not self-clear, and doing so risks masking the fault further.
- Do not attempt to access or work on the PCB yourself Gas Safe engineer
The control unit is connected to mains voltage wiring and controls all gas and safety functions. Opening the boiler casing to inspect or replace it is not a homeowner task. Attempting this without the correct training and tools is dangerous and will void any remaining warranty.
- Call a Gas Safe registered engineer to diagnose the control unit Gas Safe engineer
The engineer will use Remeha-compatible diagnostic tools to test whether the PCB has failed outright or whether the settings have simply become corrupted. They will check wiring harnesses and connections to the board before deciding whether reprogramming or a full replacement is necessary.
- Have the control unit reprogrammed or replaced as advised Gas Safe engineer
If the settings are corrupted but the board is otherwise sound, the engineer may be able to reload the correct parameters. If the PCB has failed, it will need to be replaced with the correct unit for your model. Labour for this job typically takes one to three hours.
Parts you may need
- Remeha PCB / control unit · from £280
- Wiring harness / connector loom · from £45
- Programmer / controller interface board · from £95
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 £350–£650, depending on the underlying cause.
Frequently asked questions
Can I reset an E45 fault myself to get the heating working again?
Unfortunately not in any lasting way. The E45 lockout is caused by the control unit losing its settings or failing, so pressing the reset button may briefly attempt a restart but the boiler will lock out again almost immediately. There is no homeowner check – such as topping up the pressure or thawing a condensate pipe – that addresses this fault. You will need a Gas Safe engineer to either reprogram or replace the control unit before the boiler will run reliably again.
How much does it cost to fix a Remeha E45 fault in the UK?
Most homeowners pay between £350 and £650 all in, covering the engineer's call-out, diagnostic time, and the cost of a replacement PCB or reprogramming. A new control unit for a Remeha typically costs £180–£400 for the part alone, with labour adding £100–£200 on top. Prices sit at the higher end in London and the South East and can be 10–20% lower in the North of England and Wales. If your boiler is still under its manufacturer's warranty and has been serviced annually by a Gas Safe engineer, the part cost may be covered – check your paperwork before booking a repair.
Is it worth repairing the PCB on an older Remeha boiler, or should I replace the boiler?
Remeha boilers are well built and can last 10–15 years with annual servicing, so a PCB replacement on a boiler that is only 5–8 years old usually makes financial sense. However, if your boiler is approaching 10–12 years old and this is not its first significant repair, the cost of a new PCB (potentially £450–£650 fitted) starts to compete with the deposit on a new, more efficient appliance. Ask your engineer for an honest assessment of the boiler's overall condition before committing to the repair.
Why has my Remeha boiler gone back to default settings?
The E45 code specifically flags that the control unit is either running on factory defaults because it cannot retrieve its stored configuration, or that the stored parameters have become corrupted. The two main triggers are a hardware fault on the PCB itself (often from age, a power surge, or moisture) and data corruption caused by something like a power cut mid-cycle. In either case the boiler cannot operate safely on default values, so it locks out until the correct settings are restored or the board is replaced.