Error E15

Safety first

1) If you smell gas (rotten egg smell), leave the property immediately, do not operate electrical switches or phones inside, ventilate windows/doors if it’s safe to do so and call your national gas emergency number immediately.

2) If you are unsure or uncomfortable, do not perform checks that require opening the boiler casing or touching wiring or gas components; call a Gas Safe registered engineer.

Initial homeowner checks (safe to perform)

1) Note the exact error display. Some Baxi models show E1 then more digits — record the full sequence and take a photo of the display; this helps the engineer.

2) Check other gas appliances in the property (hob, gas fire) to confirm there is gas supply. If all gas appliances fail, check the gas meter or prepayment credit and contact your gas supplier.

3) Check mains electricity to the boiler: is the boiler powered, RCD/fuse not tripped, and any external isolation switches ON? If the boiler has a visible fuse or spur, confirm it has not blown.

4) Do a controlled reset once: follow your boiler’s reset procedure (for many GA models turn the selector to R and hold for about 5 seconds, or press the reset button). Only attempt a reset once or twice. If the fault returns, do not keep resetting.

5) Check visible external connections only: ensure there are no obvious loose external leads or crushed cables at the external controls/thermostat connections. Do not remove covers or probe inside the boiler.

What a Gas Safe engineer will (or should) check and do

1) Confirm fault code and run live diagnostics with manufacturer service procedures. They will check wiring continuity between the PCB and the gas valve connectors and inspect for damaged/cracked connectors, corrosion or signs of overheating.

2) Measure gas valve coil resistance and the drive current from the PCB to confirm the valve is being commanded correctly and is within spec.

3) Check the PCB outputs and supply voltages, plus flame sensing, to determine if the issue is the gas valve itself, wiring/connectors, or the PCB.

4) Inspect for intermittent faults caused by vibration/loose crimps or terminal screws and replace/repair as required. If the gas valve or PCB is faulty they will replace the defective component and re-test the boiler for correct operation and safe combustion.

5) Carry out combustion checks and safety tests after any gas-valve or PCB work, and record work carried out for warranty and safety compliance.

When to call a professional

1) If the error returns after a controlled reset, or if you did not find any simple supply or power issue during the initial checks, arrange a visit from a Gas Safe registered engineer.

2) Any time you suspect wiring issues, component faults, or PCB failure — these require specialist test equipment and certified competence to repair safely.

3) If the boiler is under warranty, contact the installer or manufacturer service line first and provide the exact error code and any photos.

What information to provide to the engineer

1) Boiler make/model and serial number.

2) Exact error code and whether it was persistent or intermittent; include any photos you took of the display.

3) What you already checked (gas supply to other appliances, mains power, reset attempts).

Final notes

1) Do not attempt to access or repair the gas valve, internal wiring, or PCB yourself. That work is gas work and electrical work requiring a Gas Safe engineer.

2) Avoid repeated resets — if the fault persists the boiler will continue to lock out and repeated resetting can mask intermittent faults and is not a substitute for proper diagnosis.

3) If you suspect a gas leak, follow emergency gas procedures immediately. Contact a Gas Safe engineer for all gas valve, wiring or PCB repairs.