Hyundai Repair: Santa fe check engine light, transmission control module tcm, transmission control module

Question
I have a 2001 Santa Fe with about 45,000 miles. Recently while driving I felt a slight jolt and the check engine light came on. The engine seemed to loose power and was very slow coming out of a full stop. After 2-5 miles the problem seems to go away. If I remove the gas cap and re-install the check engine light goes out. This happens about 2 times per week. Could it be vapor lock? Or is it a much more serious problem with the transmission?

Answer
Most likely, this is a minor transmission-related issue.  I'm guessing that every time you tighten the gas cap, you turn off the vehicle.  This would be why the lamp goes out.  Every time the vehicle is turned off, the trasnmission will begin operating normally again until the transmission control module (TCM) again sees the problem.  

As with all check engine lamp problems, I recommend starting with reading your trouble codes.  In your case, read both the engine and transmission codes.  AutoZone and AAMCO have advertised that they'll read your trouble codes for no charge.