Lennox SLP98UHV Error Code E 310: Discharge Sensor Failure
What Does Code E 310 Mean?
Error code E310 on the Lennox SLP98UHV indicates that the discharge air temperature sensor (DATS) is shorted or reading outside its normal range. This sensor monitors the temperature of the heated air leaving the furnace and is used by the control board to manage heating output and protect against overheating.
This code is only activated during Field Test mode or specific diagnostic conditions. The control board reports the error when the sensor is shorted, but notably does not generate an error if the sensor is simply disconnected. This means the sensor itself has likely failed internally rather than having a wiring issue.
While the furnace may continue to operate without a functioning discharge sensor, it loses an important safety monitoring capability. A technician should replace the sensor to restore proper temperature monitoring. This is a relatively straightforward repair.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Discharge air temperature sensor shorted or reading out of range | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- The furnace displays E310 during a diagnostic check
- You notice the furnace producing excessively hot air without shutting down
- The sensor should be replaced at the next scheduled maintenance visit
✓ Verified against manufacturer service manual — March 2026