Lennox SLP98UHV Error Code E 200: Hard Lockout - Rollout Circuit Open
What Does Code E 200 Mean?
Error code E200 on the Lennox SLP98UHV indicates a hard lockout caused by the rollout circuit being open or having been previously open. The flame rollout switch is a critical safety device positioned near the burners that trips when it detects excessive heat outside the combustion chamber — meaning flames have escaped from where they should be contained.
Flame rollout is one of the most dangerous conditions a furnace can experience. It can be caused by a cracked or deteriorated heat exchanger that allows combustion gases to escape, a blocked flue or exhaust vent that forces flames backward out of the combustion chamber, or a combustion air supply problem. Any of these conditions can lead to carbon monoxide entering your home or a fire hazard.
Unlike soft lockouts that clear automatically, a hard lockout requires the root cause to be identified and corrected. Even if the rollout switch resets, the furnace should not be operated until a qualified HVAC technician has inspected the heat exchanger, venting system, and combustion air supply to determine why flames escaped the combustion chamber.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Blocked heat exchanger or restricted flue causing flames to roll out of the combustion chamber | Most common | ✗ Call a pro → |
| Cracked or failed heat exchanger | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Immediately — E200 is a safety-critical code that requires professional diagnosis
- Do not attempt to reset or bypass the rollout switch
- You smell burning, see scorch marks, or notice soot near the furnace
- The heat exchanger, flue, and combustion air supply all need professional inspection
✓ Verified against manufacturer service manual — March 2026