Ruud U96VA0702317MSA Error Code 58: Water Circuit Open
What Does Code 58 Mean?
A code 58 on the Ruud U96VA0702317MSA is a critical fault indicating the IFC cannot detect electrical continuity between pins 1 and 2 of connector P4 on the control board. The U96VA uses two water sensors to monitor for condensate accumulation in the collector box — a safety feature specific to condensing furnaces that produce liquid condensate during every heating cycle. When both sensors are properly installed and connected with undamaged wiring, there is electrical continuity between the P4 pins. An open circuit means something has broken that continuity.
Code 58 is distinct from code 59 (which means water is actively detected): code 58 means the sensor monitoring circuit itself is broken, not that water is present. Gas heating is blocked while cooling and fan-only modes remain available. The IFC requires the water sensor circuit to be intact to maintain the condensate safety function — without it, the furnace has lost the ability to detect a potentially damaging condensate backup.
Common causes include wiring damage between the IFC and the water sensors — whether from mechanical damage, pinching during a prior repair, or rodent activity — and a loose or unseated connection at connector P4 on the board. A water sensor that was removed during prior service work and not reinstalled will also open the circuit. A technician should inspect the full wiring path from P4 to both sensors and confirm both sensors are physically in place.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Damaged wiring or loose connection at water sensor | Most common | ✗ Call a pro → |
| Water sensor removed | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Call a technician to inspect the wiring between the IFC connector P4 and both water sensors for damage or loose connections — repairing the wiring or reseating connector P4 is required to restore gas heating
- The technician should verify both water sensors are physically installed in the collector box, as removal of either sensor during prior service work breaks the circuit continuity needed to clear code 58
✓ Verified against manufacturer service manual — March 2026