FieldBench
Lennox codes

Lennox

7 flash

Lockout

Ignition lockout

Failed to light / prove flame.

Walk 7 flash in Diagnose

3 plates — walk the one on the cabinet

First check

1 Watch one full try — do not reset

Write the Lennox ML180 code. Watch inducer, HSI glow, valve click, flame, µA. The step that dies is the repair. Resetting only burns another try into a harder lockout. HSI, gas, rod.

Expect: W

The rest of the walkthrough is Diagnose.

On the plates

  • HSI, gas cock, valve 24 VAC, rod.
  • HSI, gas, rod.

Plates that use 7 flash

Same number, other makers

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