Originally Posted by
DukeJ
How is it possible that the CEL went off by itself?
The ecu runs test while driving if it passes the code clears. This dose not mean you do not have a problem It just did not have a problem at that time.
If it is the tork converter lock up code the ecu looks at engine rpm and input shaft rpm they should match if the torque converter is locked. If they do not it codes................. meaning the ecu is commanding the torque converter to lock but is not for one reason or another.