Lennox

8 flash

Lockout

Flame lost lockout

Had flame, then lost it. Retries used up.

3 plates — walk the one on the cabinet

First check

1 Measure µA while it is running

Do not clean first and guess. Series-µA the rod on Lennox ML180 during a call. Falling µA is oxide, ground, or a dying flame. A hard drop is often the pressure switch or limit opening, not the rod. Rod, ground, downdraft after blower-on.

Expect: Typically ≥ 1.0 µA DC on this family — confirm the door card. Rising while running.

The rest of the walkthrough is Diagnose.

On the plates

Rod, ground, manifold after blower-on, vent that starves the flame.
Rod, ground, downdraft after blower-on.

Plates that use 8 flash

ML180
Merit · 80% · metal vent · LED flash
Had flame, then lost it.
Diagnose ML180 — Sign in
ML193
Merit · 93% or 80% CT · LED flash
Diagnose ML193 — Sign in
ML196
Merit · single- or two-stage · LED flash · 96%
Diagnose ML196 — Sign in

Same number, other makers

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