I have a xe80 trane
Wake up this morning with fan on but igniation off no flames
Read through your forum found my diagnostic light blinking 4 times then pause
Found the thermal protective device
Black rectangle box with 2 switches/wires
Tapped it 3 times
Turned it on
And now it works great
But my question is what to do next and if there is any part I should replace
As I want to make sure this will not happen again
Thank u

Make sure your filter/s are clean. Lack of airflow will cause the limit to open due to overheating. Normally the main high limit will reset itself when it cools off, if it isn't reseting itself, you will want to replace the limit.