ETA: Never mind...I did a search and found the issue: http://www.hyundai-forums.com/t4794-troubl...5-and-p1529.htm

I have a 2002 Sonata with a V6/automatic. The check engine light came on today while I was driving in traffic. After that I noticed that I am not able to go into gears 1 or 4. The car runs, but jerks when I try to shift between 2 and 3 or back. I can't get to the shop till tomorrow night to check the light. Does anyone know what might be causing this? The fluid level is good, btw.

Thanks!

This post has been edited by BWPerdue: Nov 18 2009, 08:06 PM

I had the exact same thing happened to my 02 Sonata GLS V6 at ~126xxx miles, so I took it in to local Hyundai dealer. They found Input speed sensor to be faulty, and tech told me a number of cases showed once the input speed sensor goes bad, soon output speed sensor follows. So to save extra labor cost later, I had both replaced (cost me ~$500 including labor, tax). Anyway, now the car has almost 131k miles and drives without any issues so far.

I just put the input sensor in this morning - it shifts better than it ever has!

Just out of curiosity, do the same symptoms happen with the output sensor, as well? Just to keep an eye on it...

I would think it'll go in to the same fail-safe mode once the output sensor goes bad. When mine was being replaced, the output sensor wasn't bad, I just told them to do the job to not worry about it going bad later (and save labor cost if you do both sensors at the same time). BTW, how involving was the installing the sensor yourself? I got mine done at the time by the dealer because I didn't have time to figure it out, instead spent $$$

This post has been edited by wbnata: Nov 22 2009, 10:02 PM

I followed the instructions by Bluesonata2002 in the link I posted above to another thread. From start to finish, including sipping on coffee as I went, it took me an hour, and I wasn't hurrying. The part cost me $67 and change from a local dealer.