York TM9V080B12MP11 Error Code 10 Red Flashes: Gas Valve Energized Without Call for Heat
What Does Code 10 Red Flashes Mean?
A 10 red flash code on the York TM9V080B12MP11 indicates the control board has detected that the gas valve is energized when no heating cycle should be active. This is a safety concern because the gas valve controls the flow of gas to the burners and should only receive power during a controlled ignition sequence. The control board has turned on both the main blower and inducer blower as safety measures to ventilate the furnace, but it will not attempt ignition.
A faulty gas valve is the most likely cause. The valve's internal solenoid or wiring may have developed a short that creates an unintended power path, causing the valve to energize independently of the control board's commands. Damaged or shorted wiring between the control board and the gas valve can produce the same result.
Shut off the furnace at the circuit breaker and contact a qualified HVAC technician immediately. This condition means gas may be flowing to the burners outside of normal control, which is a serious safety hazard. Do not attempt to work on gas valve electrical connections yourself.
Common Causes
| Cause | Likelihood | DIY? |
|---|---|---|
| Faulty gas valve | Most common | ✗ Call a pro → |
| Faulty gas valve wiring | Common | ✗ Call a pro → |
When to Call a Professional
Contact a licensed HVAC technician if:
- Immediately — an energized gas valve without a call for heat is a safety hazard requiring urgent professional inspection
✓ Verified against manufacturer service manual — March 2026