03 santa fe, manual trans, 2.4l 4cyl, will not go past 20 mph

look @ the ignition module, that is the problem

nmm

Have the codes read again. See if it has set any new ones and post them here.

Thanks for the suggestions. We'll check it out. but while we wait, the check engine light just went out while running, sitting in neutral. A good thing I suppose, but will it still provide a code?

Yes it will store the codes until cleared.

Awesome, thanks. We have to rent the code reader from autozone tomorrow. it's already been checked out for the night. i'll post the codes when we get em.

Let us know.

dfffgfhhjkl

cvbhgnjutfvv

dfreecvbnklopp

mnbhggfddsa

Ok so we didn't get any codes. But we had a number of sensors come back inconclusive. O2, cat, evap sys and EGR/VVT.

I think your transmission is going into limp mode. The code scanner you have is not equipped to read transmission codes. You need to take it to a garage that has a scanner that can read them. Post the codes here.

cat converter? plugged fuel filter?

Check your battery... if it is under 10 volts it can’t fire the sensors or fuel injectors. Try changing the battery out and see if it runs any better. The battery runs everything on newer vehicles that includes the engine computer, most parts stores offer battery and alternator test on or off of the car.