Error E10

Safety precautions:

1) If you smell gas or suspect a gas leak, evacuate the property immediately, call the gas emergency number and do not operate electrical switches or the boiler. 2) Before opening any boiler covers or working on wiring isolate mains power at the fused spur and turn off the boiler. 3) If you are not confident or not qualified to work on gas appliances or live electrical wiring, stop and call a Gas Safe engineer.

Initial checks a homeowner can safely do:

1) Note the full error code and any pattern of faults. Take a photo of the display. 2) Try a boiler reset first: follow the boiler panel procedure (usually hold the reset button or turn the selector to R and hold for ~5–10 seconds). Wait for the boiler to attempt restart and see if E10 clears. 3) Check for obvious external damage: inspect the outside probe (if you can see it) for physical damage, a disconnected lead, water ingress, or corrosion. Check that any protective cap/shield is intact and the cable is not chewed or crushed. 4) Check wiring run visually: where the external probe cable enters the building, look for damage or moisture ingress.

Specific diagnostic and simple fix steps (only if comfortable and safe):

1) If you can safely access the external probe housing (outside) without disturbing the boiler electrics, ensure the probe is fixed properly and not loose. Replace or re-seat any simple push-fit cap. 2) If the cable to the probe is visibly damaged or disconnected at an obvious external junction, you may temporarily protect the cable from further water ingress (seal with tape) but do not attempt internal splices unless qualified. 3) If you have basic electrical skills and the boiler is isolated from mains power: remove the boiler service panel only if manufacturer guidance permits homeowner access (many manufacturers advise against this). Locate the external probe terminal block or connector and check it is fully seated. Do not touch live parts; keep power isolated. 4) With power isolated, you can perform a basic continuity/resistance check of the probe cable and probe using a multimeter: measure resistance across the probe terminals at the boiler connector. The resistance should change if you warm or cool the probe (for example, warming the probe slightly in your hand or with warm water will cause a resistance change). Exact resistance values vary by sensor type—consult the boiler manual or component specifications before relying on absolute numbers. If the resistance is open-circuit (infinite) or short-circuit (near zero) the probe or cable is faulty. 5) If the connector is corroded or loose, cleaning and re-seating the connection can sometimes restore operation, but this should be done with power isolated and ideally by a qualified engineer to ensure safe reconnection and correct sealing against moisture.

When to call a professional:

1) If the E10 code does not clear after a reset and simple external checks, call a Gas Safe registered engineer. 2) Any work inside the boiler, replacement of the probe, replacement/repair of wiring running into the house, or investigation of the PCB/communication wiring must be carried out by a qualified engineer. 3) If the fault is intermittent, recurring, or accompanied by other faults (lockouts, pressure warnings, condensate or flue problems), have a professional diagnose the system to avoid unsafe repairs.

What the engineer will likely check/replace:

1) Verify wiring continuity and insulation; locate moisture or cable damage. 2) Measure probe resistance and compare against specification; replace external probe if faulty. 3) Inspect connectors and terminal blocks for corrosion and poor contacts; repair or replace as needed. 4) If wiring and probe are good, investigate PCB or sensor input circuitry and repair or replace components as required.

Record-keeping and next steps:

1) Keep a note or photo of the error code, times and any patterns. 2) If the boiler is under warranty or service contract contact the manufacturer or service provider before attempting further DIY repairs. 3) Avoid repeated resets if the fault returns — repeated lockouts can mask underlying issues and potentially lead to additional faults. 4) Always use a Gas Safe registered engineer for final repairs and for any internal work on the boiler.