Ruud U802VA050317MSA Error Code *T057_F: Inducer Hi Pressure Switch Won't Close (Transient, Two-Stage Only)
What Does Code *T057_F Mean?
Code T057_F on the Ruud U802VA indicates that the high-stage inducer pressure switch failed to close when the inducer motor is running at high speed. This code applies only to two-stage furnace models. The 'T' prefix means this is a transient (intermittent) fault.
Two-stage furnaces have separate pressure switches for low-stage and high-stage operation. The high-stage pressure switch requires more draft (stronger negative pressure) to close because the furnace burns more gas at high fire and needs correspondingly more exhaust capacity. A partial vent blockage may allow enough draft for low-stage operation but not enough for high-stage.
The most common cause is a partially blocked exhaust vent that restricts airflow just enough to affect high-stage draft. The furnace may operate normally on low stage but fail when it tries to ramp up to high stage on colder days. Less commonly, the high-stage pressure switch itself may be failing, or the inducer motor may not be reaching full speed.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Blocked vent or insufficient draft at high stage | Most common | ✓ DIY fix → |
How to Fix It: Clear the Exhaust Vent of Partial Blockage
What You'll Need
Steps
- Turn off electrical power at the breaker or power switch AND shut off the gas supply valve Locate the furnace circuit breaker and flip it to OFF, or use the power switch on or near the furnace. Turn the gas shutoff valve to the OFF position (perpendicular to the pipe). If you smell gas at any point, leave the area immediately and call your gas company.
- Inspect the exhaust vent termination outside Find where the furnace exhaust vent exits your home. Since this code relates to insufficient draft at high stage, look for partial blockages that may not completely block the vent but restrict airflow — ice buildup around the edges, partial debris accumulation, or a bird screen that has become clogged with lint or frost.
- Clear any blockage or restriction Remove any ice, debris, or buildup from the exhaust vent opening. If there is a screening or guard on the vent, make sure it is clean and not restricting airflow. Also check and clear the combustion air intake pipe if your system has a separate one.
- Check for vent pipe restrictions inside Visually inspect any accessible sections of the vent piping. Look for sagging sections that could trap condensation and partially block airflow, or joints that may have shifted. Long horizontal vent runs are more susceptible to partial blockage from condensation buildup.
- Restore gas and power, then test Turn the gas supply valve to ON and restore electrical power. Set the thermostat several degrees above room temperature to encourage the furnace to run on high stage. Monitor whether the furnace successfully operates on high fire without triggering the code.
When to Call a Professional
Contact a licensed HVAC technician if:
- The exhaust vent is clear but the code still appears during high-stage operation
- The furnace works on low stage but consistently fails on high stage
- The inducer motor sounds different between low and high speed operation
- You notice condensation or water in the vent piping
- The vent run is unusually long or has many elbows (possible design issue)
Sources
✓ Verified against manufacturer service manual — March 2026