13
Lost flame sense / flame-failure family
This code typically points to
- Failure to sense flame after burners light
Next checks to confirm
- Public snippet says: failure to sense flame — check status display, function code 11 expected in that branch, then follow function-code guide
- Full dedicated code-13 tree not exposed
Escalation
Ignition/flame retry family
Reset behavior
Clears on successful flame sense or lockout reset.
Urgent
Fix now