Technical directory · Combustion
Flame sensor fouling
A flame sensor proves flame to the control board; an intermittent shutdown can have causes beyond a dirty rod.
What to observe
Record fault codes and timing of ignition versus shutdown before service.
A field example
If ignition succeeds briefly and the furnace shuts off, record the exact sequence and code. A sensor rod may need attention, but weak grounding or another control fault can create a similar symptom.
What the written work should say
A certified technician can inspect the sensor and circuit, clean or replace as indicated, then verify stable operation.
Where this task stops
Repeatedly cleaning the sensor without diagnosing its circuit may miss another fault.