Check Engine Light on // Can't go 4th gear
 

I have a 2002 Hyundai Accent (Automatic Transmission)
Milage: 76,000

I've had this problem for about 4 months now and its getting kinda annoying. The problem is that when i have overdrive *ON* my car won't catch 4th gear. When i drive at low MPH around 30 or below its fine. But when i hit aroundd 40mph my tranny slips. Check engine light came on and i got the code awhile ago but forgot. Basically i got rid of the check engine light and the tranny slipping problem by putting Overdrive *OFF* When Overdrive is off it prevents my car from going to 4th gear (getting rid of the 4th gear slippage) So basically my car only goes to 3rd gear. I do not go on Highways because when i go 60mph...my RPM is at around 4.5 almost 5 RPM. I dont wanna go on the freeways because that would just get me at a high RPM and scared to blow the engine. i've been going inside way for months now and do not have a tranny problem. I tried to turn Overdrive *ON* the other day to see if i still have the tranny slippage months later...when i hit around 40mph it slipped like it did months ago so i quickly turned overdrive back *OFF* i wanna fix the problem now but not sure what the problem is. I remembered on a different forum that its the speed sensors (pulse generators) and that i need to get it replaced? anyone have any comment on what the problem could be? I remember i got the code and it had to do with the transmission but im not sure if the transmission is the problem because it runs perfectly fine with overdrive OFF. any type of help would be greatly appreciated. Thanks. (Keep in mind that my car is AUTOMATIC transmission.

P.S. I Changed the transmission fluid when i first had the problem and it did not fix the tranny slipping problem.


-Jimmy