Remeha E.02.17 Fault Code: Causes, Fixes & Repair Costs
What does the Remeha E.02.17 fault code mean?
The E.02.17 code (also shown as E02.17) means the boiler's main control board has lost communication with its internal safety sub-unit — known as the CU-GH or CSU. These two components constantly exchange data to confirm that all safety-critical processes are running correctly. When that dialogue times out or breaks down entirely, the boiler locks out as a precaution. This is an internal electronic fault rather than a problem with gas supply, water pressure, or pipework, so the fix almost always involves an engineer checking wiring and potentially replacing the CU-GH printed circuit board.
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
- Temporary power glitch or electrical spike Common
A brief voltage fluctuation or power cut can interrupt the communication handshake between the main PCB and the CU-GH safety unit. If this is the cause, a single boiler reset will often clear the fault permanently.
- Loose or damaged internal wiring or connectors Common
The wiring loom and plug connectors linking the main board to the CSU safety unit can work loose over time, corrode, or sustain heat damage. A related fault in the same E.02.xx family specifically points to checking internal cabling and the earth connection at the mains socket as first diagnostic steps.
- Failed CU-GH or CSU safety board Sometimes
If neither a reset nor a wiring check resolves the fault, one or both of the electronic boards has likely failed permanently. Remeha's own documentation lists replacing the CU-GH PCB as the primary corrective action when the restart does not work. In some cases both the main board and the CSU chip need to be replaced together.
- Corrupted internal parameters or detection failure Rare
Occasionally the boiler's internal configuration data becomes corrupted — for example after a firmware issue or a hard power loss — causing the two boards to fail to recognise each other. An engineer may be able to run an automatic detection routine before resorting to board replacement.
How to fix it
- Reset the boiler once DIY safe
Locate the reset button on the boiler's control panel and press it to attempt a restart. Only do this once — repeatedly resetting a locked-out boiler can mask the underlying fault and is not recommended. If the boiler fires up and runs normally for several days without the code returning, a one-off power glitch was likely to blame.
- Check the mains socket earth and power supply DIY safe
Confirm the boiler's mains plug or fused spur is fully seated and that other appliances on the same circuit are working normally. A loose earth connection at the socket is a known contributing factor for E.02.xx communication faults on Remeha Ace-series boilers. Do not open the boiler casing or touch any internal wiring yourself.
- Call a Gas Safe registered engineer to inspect internal wiring and connectors Gas Safe engineer
An engineer should open the boiler casing and inspect the wiring loom and plug connectors between the main PCB and the CU-GH safety unit. Loose pins, heat-damaged insulation, or a poor connection here can cause the communication timeout. Re-seating or replacing connectors is often a lower-cost fix than a full board swap.
- Engineer to replace the CU-GH PCB (and CSU if required) Gas Safe engineer
If wiring checks draw a blank, the CU-GH printed circuit board is the primary suspect. Remeha's fault documentation explicitly lists board replacement as the resolution for E.02.17. The CU-GH is a proprietary Remeha part, so the engineer will need to source a genuine replacement. In some cases the main board and the CSU safety chip are replaced as a pair to guarantee reliable communication between them.
Parts you may need
- Remeha CU-GH printed circuit board (main control PCB) · from £280
- CSU safety sub-unit / safety chip assembly · from £120
- Internal wiring loom / connector set · from £35
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 £250–£480, depending on the underlying cause.
Frequently asked questions
Can I fix Remeha E.02.17 myself?
The only safe DIY action is a single boiler reset. If that clears the fault and it does not return, a temporary power glitch was probably to blame. Everything beyond that — opening the casing, checking internal wiring, or replacing the CU-GH board — must be carried out by a Gas Safe registered engineer. Working on internal boiler electronics without the correct qualifications is both dangerous and illegal in the UK.
How much does it cost to fix E.02.17 in the UK?
Most homeowners pay somewhere between £250 and £480 all-in, which covers the engineer's labour and the cost of a replacement CU-GH PCB. If only wiring or connectors need attention the bill will sit at the lower end. Note that if both the main board and the CSU safety chip need replacing simultaneously — which Remeha engineers sometimes recommend — costs can push above £500, but this is less common. Always get a written quote before authorising parts.
What is the CU-GH board on a Remeha boiler?
The CU-GH is Remeha's proprietary control and safety board — effectively the brain of the boiler. It manages the gas valve, hydraulic system, ignition, and all safety interlocks. It also communicates continuously with a dedicated safety sub-unit (CSU) to confirm that critical processes are working correctly. When that communication breaks down, the boiler raises E.02.17 and shuts down to prevent unsafe operation.
My Remeha Tzerra Ace is only a few years old — is the PCB likely to fail already?
PCB failures on relatively young boilers are less common but do happen, often triggered by electrical spikes, persistent damp inside the casing, or a manufacturing defect. Before assuming the worst, ask the engineer to check the wiring and connectors first, as a loose connector can mimic a full board failure at a fraction of the cost. If the boiler is still within its manufacturer's warranty period, contact Remeha directly before commissioning any paid repairs, as the parts may be covered.