Every current dryer, washer and refrigerator is run by a control board that acts on what its sensors report. When a reading falls outside the expected range, the board stops the cycle and shows a code. Most owners read that as “the machine is broken.” A technician reads it as a sentence: the control saw something it did not like and is telling you where to look.
The dryer: moisture, exhaust heat and a one-time fuse
Open the dryer door and find the two metal strips near the lint filter. Those are the moisture bars. Damp fabric brushing across them completes a weak circuit; as the load dries, the circuit closes less often and the board ends the cycle. Bars coated with fabric softener film make the control think the clothes are dry long before they are, which is why auto-dry sometimes quits after ten minutes.
In the exhaust path, a thermistor reports air temperature so the board can cycle the heater. Next to it sits a thermal fuse, a safety device that opens permanently if the exhaust gets too hot. A dryer that tumbles with no heat very often has a blown thermal fuse, and the fuse almost never fails on its own: it is reacting to a restricted vent. Colorado’s dry air makes lint light a...