Ruud U802VA050317MSA Error Code T087_F: Power Board Temp Sensor Fault
What Does Code T087_F Mean?
Fault code T087_F on the Ruud U802VA indicates that the temperature sensor built into the power board (IFC) has failed or produced an out-of-range reading. This internal sensor monitors the operating temperature of the control board's own electronics, providing thermal protection to prevent the board from overheating.
With this sensor reporting a fault, the IFC's self-monitoring capability for board temperature is compromised. In installations where the furnace room has poor ventilation or high ambient temperatures, board electronics could potentially overheat without the normal protective response. The T (transient) prefix indicates this was an intermittent observation.
Because the temperature sensor is integrated directly into the control board circuit rather than being a standalone replaceable component, T087_F typically means the control board itself needs evaluation. It is possible the sensor failed due to a thermal event that has already damaged the board, or the board may simply have a component that has drifted out of specification.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty temperature sensor on control board | Most common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Schedule a service call — a technician should evaluate the control board using the Bluetooth contractor app and inspect for signs of heat damage
- A technician should also verify that the furnace installation area has adequate ventilation to prevent board overheating
- If the board shows signs of thermal damage or the fault becomes persistent (escalates to alarm level), board replacement will be needed
✓ Verified against manufacturer service manual — March 2026