Ruud U802VA050317MSA Error Code A093_F: Internal Control Fault Detected
What Does Code A093_F Mean?
Fault code A093_F on the Ruud U802VA indicates that the IFC board has detected an unspecified internal fault, triggering a hard lockout. This code is also set when voltage is detected unexpectedly on the gas valve contacts and does not go away when the inducer is shut off — a condition that indicates a welded gas valve relay.
The U802VA documentation notes that lockout conditions can normally be cleared by cycling power, but a hard lockout like A093_F requires the underlying fault to be corrected first. Simply power cycling without fixing the root cause will result in the furnace immediately re-entering the lockout state.
If a welded gas valve relay is the cause, the control board cannot interrupt power to the gas valve, which is a safety hazard — gas could potentially flow when it should not. For a general internal board fault, the electronics have experienced a failure that the self-diagnostic system detected but cannot specifically identify. In both cases, the control board will likely require professional evaluation and replacement.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Failed control board (internal fault) | Most common | ✗ Call a pro → |
| Welded gas valve relay on control board | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Call a technician immediately — this is a hard lockout requiring professional diagnosis
- If a welded gas valve relay is suspected, turn off the manual gas supply valve before calling
- The control board requires evaluation and likely replacement; do not power cycle repeatedly without professional diagnosis
✓ Verified against manufacturer service manual — March 2026