FieldBench
Lennox codes

Lennox

5 flash

Hazard

Rollout

Flame containment. Hazard.

Walk 5 flash in Diagnose

3 plates — walk the one on the cabinet

First check

1 Treat this as flame outside the exchanger

Do not reset the Lennox ML180 rollout and walk away. Write the code, kill the call, and look for flame at the burners, crossover, and vestibule before you do anything else.

Expect: No flame outside the exchanger. Burners seated. Crossover lit.

If pass: Still inspect secondary / flue / condensate before you reset.

The rest of the walkthrough is Diagnose.

On the plates

  • Exchanger, burners, flue. Reset only after the cause is gone.
  • Exchanger, burners, blocked metal flue, downdraft. Reset only after the cause is gone.

Plates that use 5 flash

Same number, other makers

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