Lennox SLP98UHV Error Code E 205: Gas Valve Relay Contact Shorted
What Does Code E 205 Mean?
Error code E205 on the Lennox SLP98UHV indicates that the gas valve control relay contact on the control board has shorted (welded) closed. This means the relay that controls gas flow is stuck in the energized position, which could allow gas to flow to the burners when it should not.
This is a serious safety condition. Under normal operation, the control board opens and closes the gas valve relay to precisely control when gas flows to the burners. When the relay contacts weld together, the board loses the ability to shut off gas flow through this circuit. The control board detects this condition and locks out the furnace as a safety precaution.
The control board will need to be replaced to fix this issue. A shorted relay is an internal board failure that cannot be field-repaired. A technician should also inspect the gas valve itself to ensure it was not damaged by the relay malfunction.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Gas valve relay on control board has welded or stuck closed | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- This code requires immediate professional attention — the gas valve relay is shorted
- You smell gas or notice the burners behaving abnormally
- The furnace will not operate and displays E205
✓ Verified against manufacturer service manual — March 2026