FieldBench
Lennox codes

Lennox

1 flash

Hazard

Unexpected flame

Flame with the valve off.

Walk 1 flash in Diagnose

3 plates — walk the one on the cabinet

First check

1 Shut the gas cock first

On Lennox ML180 the rod sees flame with the valve de-energized. Shut the cock. If flame stays, the valve is leaking — replace it. Do not jump or energize it as a test. Shut the cock. Leaking valve.

Expect: Flame dies when the cock is shut.

If fail: Leaking valve. Replace. Do not leave the unit.

The rest of the walkthrough is Diagnose.

On the plates

  • Shut the cock. Leaking valve.

Plates that use 1 flash

Same number, other makers

1 flash on Lennox is not the same code on these plates.