Hyundai Repair: 1999 Sonata check engine on and off, speed sensors, control modules

Question
Hi,

we have 1999 sonata V6. Very Recently we had the spark plugs and wiring done at the dealer. But we are getting the sudden jeerk and check engin ON. It happens some times and sometimes when restart the engine after some time check engine is OFF. Its too strange. It come up sometimes while i try to give more gas for pickup of speed.

Can you suggest what could be worng. We already spent lot of bucks.

Thanks,
Laxmi

Answer
There are many, many things that could cause your symptoms and the check engine lamp.  My primary suspicion is one of the transmission speed sensors, but I don't really have enough information to reach a good conclusion.

To determine the nature of the problem, I'll need the diagnostic trouble codes from the engine and transmission control modules (ECM and TCM).  Once I have this, I can advise you on how to proceed with diagnosis and/or repair.