F61 Fault — Fuel valve cannot open

What does F61 mean?

The boiler's gas valve is unable to open. This can be due to wiring issues, a faulty gas valve, or a problem with the main circuit board. On older systems (MK1), a high resistance thermal fuse can also cause this.

• Cable harness supply line to the gas valve is defective (short to earth, short circuit)
• Gas valve defective
• PCB defective
• MK1 thermal fuse with a high resistance

Click steps to track your progress.

1. 1

   Check the resistance across the gas valve (should be 40-50 ohms, requires specialist tools).

2. 2

   Check the continuity of the cable harness connecting to the gas valve (requires specialist tools).

3. 3

   On MK1 systems, check the thermal fuse for high resistance (requires specialist tools).

4. 4

   If resistance and continuity are fine, the PCB may be faulty (contact a technician).