E0
Furnace lockout due to excessive number of ignition retries
This code typically points to
- Failure to establish flame
- No gas to burners
- Front cover pressure switch stuck open
- Bad igniter or igniter alignment
- Improper orifices
- Coated/oxidized or improperly connected flame sensor
- Intermittent gas supply
- Lazy burner flames from improper gas pressure or restricted flue/combustion air
- Improper induced-draft blower performance
Next checks to confirm
- Locate/correct gas interruption
- Check front-cover pressure switch operation and wiring
- Replace or realign igniter
- Check/clean flame-sense signal
- Inspect flue piping for blockage/length/elbows/termination
- Verify induced-draft performance
Escalation
Three total ignition tries, then lockout; auto-reset after one hour
Reset behavior
Thermostat off for more than 5 seconds and less than 20 seconds, then back on; or disconnect power for at least 5 seconds; auto-reset after one hour.
Urgent
Fix now