Rheem R802VA07542117MSA Error Code T081_F: Return Air Sensor Fault
What Does Code T081_F Mean?
Fault code T081_F on the Rheem R802VA indicates that the return air temperature sensor has failed or is reporting a value outside the expected operating range. This sensor is a thermistor mounted in the return air section of the furnace that monitors the temperature of air flowing back into the furnace from the home.
The R802VA uses this sensor as part of its airflow management system. When return air temperature data is unavailable or erroneous, the IFC cannot accurately calculate airflow efficiency or detect abnormal temperature conditions. The T (troubleshooting) prefix indicates the fault is an intermittent condition rather than a full alarm lockout, so the furnace may continue to operate in a degraded state.
Common causes include a thermistor that has drifted out of specification, a wire that has become disconnected at the sensor connector or at the control board, or corroded connector pins. Because the sensor is typically mounted in the return air duct area, condensation or debris contamination can also degrade the thermistor over time.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Failed or open return air temperature thermistor | Most common | ✗ Call a pro → |
| Disconnected sensor wiring | Common | ✗ Call a pro → |
| Corroded sensor connector | Uncommon | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Schedule a service call — the return air temperature sensor needs to be tested and likely replaced
- A technician should also check the wiring and connectors to the sensor before replacing the thermistor itself
- If the fault reappears after sensor replacement, a technician should inspect the connector at the control board for corrosion
✓ Verified against manufacturer service manual — March 2026