I have a 2000 Sonata that has the code P0720 ( from auto zone).... What seems to happen is you are driving down the road and all ofa sudden the car downshifts ( rpms go up).... Also when you stop, it like the car is bogged down when you go to take off , you go slowly ( put gas pedal to the floor)until it picks up speed and I am missing a couple of gears.... This has been happening for awhile..
I havent used the car for a few weeks and took it out yesterday and drove it for about 13 miles and nothing happened...
My other vehicle was in a ACCIDENT and I really need to know if this is a sensor or tranny problem...

 

I'm curious as to what your Hyundai dealer told you when you called them up...or did you call them yet?

WheelBroker1 [sm=americanasmiley.gif]

 

Wheelbreaker,
I haven't called them yet...

 

Code P0720 is the output speed sensor, located on the top rear of the transmission and held in place with a 10 mm bolt. You may need to remove the air cleaner box and move the wiring to see it.

 

I had this problem myself on my 99 Sonata. The take off (power) wasn't very good and the car would jerk violently to the point where I was unable to drive it anymore. The check engine light came on and it was the code P0720 (output speed sensor.) It was a costly piece of plastic ($250.00 Canadian.) It's actually easy to make this repair yourself if this is what's causing your problem. However good luck trying to find the part!

Since I made the repair the car does not jerk anymore and the speed in which the car takes off is back to almost 100%. However I do notice from time to time that I have to put the pedal to the metal because this car seems to not have a lot of force.

I think the Sonata is a beautiful car however I regret buying it. There is alway one problem after the other and the price for the parts are expensive!!! In my opinion the Sonata is a fragile car, it cannot take a beating. Is it just me or are there a lot of defects in this model of car? It seems to me that a lot of people with Sonata's tend to have the same occuring problems over and over again.

Any ways... if the check engine light is reading "output speed sensor P0720" then once you change the piece your problem should 100% fixed (or close to 100%.)
If you wait too long to changethe sensor then you might end up with the serious problem thatI experienced, the car jerking between gears.