Ruud U96VA0702317MSA Error Code 57: High Pressure Switch Open, Inducer on High Speed
What Does Code 57 Mean?
A code 57 on the Ruud U96VA0702317MSA is a critical fault indicating the high pressure switch failed to close when the inducer was running at high speed. This fault can occur at any point during a high-fire heat call, after the pre-purge and blower-on delay periods have completed. When code 57 occurs and the low pressure switch remains closed, the IFC attempts to switch to low-fire heating to try to satisfy the thermostat call rather than shutting down entirely. This means the furnace may still produce some heat but at reduced capacity — high-stage heating is disabled.
The high pressure switch requires greater negative pressure to close than the low pressure switch, making it more sensitive to conditions that reduce draft. Blocked exhaust or intake vent terminations — from ice, snow, bird nests, or other debris — are the most common cause. Vent pipe runs that exceed the maximum allowable length or elbow count reduce draft pressure, particularly for high-fire operation. A deteriorating inducer motor that cannot reach full speed, disconnected or split pressure switch hoses inside the furnace, or a faulty high pressure switch are other causes. High-altitude installations may also struggle to generate enough negative pressure for high-stage operation.
Check exterior vent terminations for visible obstructions as a first step. Persistent or recurring code 57 requires a technician to fully evaluate the venting system.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Vent blockage or improper termination | Most common | ✗ Call a pro → |
| Faulty inducer or pressure switch | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- If vent terminations are clear and code 57 recurs, call a technician to inspect pressure switch hoses, measure draft pressure at the switch tap, and verify vent pipe lengths and elbows are within specification
- The technician should test the high pressure switch and replace it if it fails to close at the correct pressure value, and evaluate whether a high-altitude kit is needed for elevated installations
✓ Verified against manufacturer service manual — March 2026