Overview
E38 on a Keston C36 combi means the boiler has detected a fault with the reset key / reset circuit on the front fascia. In manufacturer documentation this is normally reported as a reset key fault and the recommended action is to replace the fascia PCB (the small control board behind the user controls). In some cases the underlying cause can be a faulty reset switch, a damaged or loose 13‑way connector between the fascia and the main control box, corrosion or water ingress to the fascia PCB, or a failed fascia PCB itself. Severity is moderate: this fault typically puts the boiler into lockout or prevents normal operation of the user controls and reset function, so you will likely lose heating and/or hot water until it is cleared. It is not usually an immediate gas safety danger (there is no specific indication of gas leakage), but it does affect safe reset and control functions. Basic checks and a power-cycle can be done by a competent homeowner, but replacing the fascia PCB or doing internal electrical repairs on a gas appliance should be carried out by a Gas Safe registered engineer. If you are not confident working with live electrical connections and appliance internals, stop and call a professional.
Possible Cause: Reset key fault – replace fascia PCB
Troubleshooting Steps
Safety precautions:
1) Before touching the boiler isolate the electrical supply at the mains isolator/fused spur and, where applicable, turn off the gas supply. Do not work on the appliance with power applied. Wear gloves and eye protection if you are opening the casing. If you are unsure about any step, call a Gas Safe registered engineer.
Initial checks a homeowner can do (no panel removal):
1) Note the error code and any other codes shown on the display and the boiler model/serial. This helps the engineer.
2) Try a simple reset: press the boiler reset button once, wait a minute and observe. If the code returns, try the next steps.
3) Power‑cycle the boiler: switch off at the isolator, wait 60–120 seconds, then switch back on. Observe if the E38 returns on start up.
4) Check the mains supply: confirm other electrical items in the house work and any fuse or RCD hasn’t tripped. (If you have the installer display options, ensure mains voltage is within expected range — low voltage <180V can cause other faults.)
5) Visually inspect the fascia for obvious damage, melted plastic, signs of water ingress or condensation on/around the control knobs.
If you are comfortable and competent to inspect the fascia PCB (only proceed if you understand the risks):
1) Isolate the electrical supply at the mains/fused spur and ensure the boiler is dead. Do not rely on the front display power alone.
2) Remove the outer case and fascia following the boiler manual: remove the screws holding the fascia, pull the fascia forward, remove the user control knob and undo the locknut securing the fascia PCB.
3) Locate and unplug the 13‑way connector between the fascia PCB and the control housing. Inspect the connector, the ribbon/cable and the PCB for burn marks, loose pins, corrosion or moisture damage.
4) Refit/seat the connector firmly and reassemble the fascia. Restore power and check whether the E38 clears. If reseating the connector clears the error, leave the boiler running and monitor; the connector may be the intermittent fault.
Diagnosis and next steps:
1) If the error returns immediately or you see damaged components (burnt traces, cracked switches, corrosion), the fascia PCB is likely faulty and should be replaced.
2) If the cable between fascia and main control box is visibly damaged, that cable or its connectors may be the cause. Replacement or repair of wiring/connector should be done by an engineer.
3) If reseating the connector sometimes clears the fault but it reappears intermittently, replacement of the fascia PCB is recommended because intermittent electrical faults can reintroduce unsafe conditions.
Replacement and final notes:
1) The factory troubleshooting and parts list identify the fascia PCB as the usual replacement item for E38. The manual gives mechanical steps for removing and fitting the fascia PCB, but replacing PCBs and testing a gas appliance should be performed by a Gas Safe registered engineer.
2) Do not try to bypass the reset function or jury‑rig controls. Do not run the boiler if you suspect damage to safety or control electronics.
3) When you call an engineer, tell them: boiler model (Keston C36 Combi), serial if available, the E38 error, what you tried (reset, power‑cycle, connector reseat), and any visible damage. That helps speed diagnosis and repair.
If the fault persists after the above checks, or if you are not comfortable opening the boiler, contact a Gas Safe registered engineer to inspect and replace the fascia PCB or repair wiring. They have the training to handle internal electrical repairs and to safely recommission the appliance.
Helpful Resources
Boiler Manual
Download the official PDF manual for the Keston C36 Combi Gas Boiler.