Error E10

Safety precautions:

1) Before doing anything isolate the electrical supply to the boiler at the fuse or isolator and switch off the room thermostat/controls. Do not work on gas or live electrical components unless you are a qualified engineer. If you must remove the boiler casing, ensure power is off and the boiler is cool. Keep a record (take a photo) of wiring positions before disconnecting anything.

2) If you are at all unsure, or if the boiler shows multiple fault codes, or if there are signs of water ingress, corrosion, gas smell, or burning, stop and call a qualified engineer immediately.

Initial checks a homeowner can do safely:

1) Try a simple reset first: switch the boiler off at the isolator for 30 seconds, then back on and see if E10 clears. Some sensor faults will reset if caused by a temporary communication glitch.

2) Check the outdoor sensor physically (if accessible): confirm the probe is present at its external location, not broken, and the cable looks intact and not rodent-chewed or water-damaged.

3) Check for additional displayed error codes or messages and note them down; they may give extra clues (e.g., wiring/PCB faults).

Specific diagnostic and fix steps (for competent DIYers only):

1) Isolate electrical supply to the boiler and wait until internal components are not live. Remove the boiler casing following the manufacturer manual instructions.

2) Locate the outdoor sensor cable and connector on the boiler PCB or terminal block (refer to the manual for the exact location). Check the connector is fully seated and locked in place.

3) Inspect wiring and connector for corrosion, water ingress or physical damage. If a connector is corroded or wires are loose, clean the connector (if minor corrosion) and reseat firmly. Replace the connector if visibly damaged.

4) If you have a multimeter and know how to use it safely: with power still isolated, measure continuity of the sensor wiring back to the sensor to confirm the cable is intact (or measure the sensor resistance if the manual gives a reference). A quick functional check is to disconnect the sensor and gently warm/cool the probe (cup in hand or with a cool damp cloth) and observe if resistance/reading changes — a live change indicates the probe responds to temperature. Do not apply heat sources that could damage the probe.

5) If wiring is intact but the sensor shows no change or an open circuit, the sensor is likely faulty and requires replacement. Use the correct replacement part specified for your model.

6) If wiring, connector and sensor appear OK, and E10 persists, there may be an internal control/PCB fault or a damaged sensor input on the board — leave further diagnosis to a qualified engineer.

7) After any reconnecting or replacement, restore power, then restart the boiler and observe for E10. If it reappears, document what you tested and call a professional.

When to call a professional:

1) If the initial reset does not clear the fault; if you find damaged wiring that needs replacement; if the sensor replacement is required; if there are any other fault codes present; or if you are not confident performing the electrical checks, call a Gas Safe registered heating engineer.

2) Any work that involves the gas supply, PCB replacement, or internal electrical repairs must be carried out by a qualified engineer. Persistent or intermittent sensor errors can also indicate a failing PCB or other control issue that needs professional diagnosis.

Additional notes:

1) Consult your boiler user manual for the exact sensor terminal locations and any model-specific instructions before opening the casing. 2) Keep a clear record of what you checked and any steps taken to help the engineer diagnose quickly if you call one.