Error 1065 B

Safety precautions:

- If you smell gas, evacuate the property immediately and call the gas emergency number — do not investigate the boiler.

- Before doing any checks that involve the boiler internals, switch the boiler off at the programmer and isolate electrical power at the fused spur or consumer unit. If you are unsure, stop and call a Gas Safe engineer.

- Do not attempt to alter gas pipework, the burner, or sealed combustion parts yourself.

Initial homeowner checks you can safely do:

1. Reset the boiler: use the boiler reset method (press and hold the reset button for about 3 seconds or follow the dial reset instruction for your model). Note whether the 1065 B code returns immediately or after some operation.

2. Check system water pressure on the pressure gauge — it should be about 1.0–1.5 bar when cold. If pressure is below 1 bar, follow the manufacturer’s instructions to repressurise the system to about 1–1.5 bar and then try a reset. If pressure is high (above 2.5 bar) you may have a leak or PRV issue; do not overfill.

3. Look for visible leaks around pipework, radiators and the pressure relief/discharge pipe. If the system is losing pressure continuously you may have a leak that needs repair.

4. Note and record any additional display cause codes or messages (use the quick info/spanner button). Take photos of the display and error code to show the engineer.

Basic diagnostic steps (only if comfortable and with power isolated):

1. Isolate electrical power to the boiler at the fused spur. Wait a few minutes.

2. Remove the outer casing only if you are comfortable doing so and only to the extent allowed in the user manual. Inspect the wiring harness that runs to the pressure sensor (pressure transducer) for loose connectors, damaged wires, signs of corrosion or water ingress. The sensor is typically mounted on the hydraulic block or pipework and has a small electrical plug.

3. If a connector is visibly loose, corroded or pushed out, reseat it firmly and ensure the locking clip engages. Refit the casing, restore power and attempt another reset.

4. If wiring is frayed, broken or the sensor shows signs of water damage, do NOT attempt to jury‑rig replacements yourself. Photograph the damage and call a professional.

When to call a professional:

- If the boiler still shows 1065 B after reset and basic connector checks.

- If you had to remove covers and found damaged wiring, a bad connector, or a faulty sensor.

- If you are not confident isolating power or accessing the internal components.

A Gas Safe‑registered engineer will safely isolate gas/electrics, perform insulation and continuity checks, test the pressure transducer with a multimeter, check the PCB input, and replace the pressure sensor or repair wiring as required. They will also check the hydraulic block and overall system pressure behaviour to ensure there isn’t an underlying leak or PRV fault.

Final notes:

- The typical sequence is: try reset → check system pressure and repressurise if low → inspect and reseat connectors (power off) → call a Gas Safe engineer if fault persists.

- Do not attempt gas or sealed‑system repairs yourself. Document error codes and any observations (photos are helpful) before the engineer arrives to speed diagnosis.