The flame was lost five times (four recycles) during the heating cycle. The furnace locks out for one hour and then restarts.
Homeowner part this code names: furnace flame sensor.
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York TG9S 8 red flashes means the flame was lost five times, which the manual also calls four recycles, during the heating cycle. Then a one-hour lockout. The checks are low gas pressure, a dirty or faulty flame sensor, and a faulty gas valve. Seven red flashes is the code for flame that never established. Continuous amber is the low-current warning, below 1.5 microamps, while the furnace may still run.
Likely causes
- Low gas pressure
- Dirty or faulty flame sensor
- Faulty gas valve
Safe checks for 8 red flashes
- Write down the 8 red flashes. The one-hour restart is not a repair
- Techniciancheck gas pressure, the flame sensor and the gas valve
Capacitors can hold a charge after the power is off. Safety terms.
When to call a pro
Call a licensed HVAC technician if the burners light and then go out until 8 red flashes appear.
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Parts & tools for this fix
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Furnace flame sensor: guide
In this code: Dirty or faulty flame sensor
Nut driver set: guide
In this code: Panels and parts on a furnace are held by hex-head screws; a nut driver grips them without stripping.
See the guide for what to look for when buying one.
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