I have a 2001 sonata with a list of various problems. Among them is the "limp" mode where my transmission

- My timing and serpentine belt need to be changed. (overdue)

- "limp" mode where my transmission gets stuck in 3rd gear

- Throwing the following codes.

P0715 (no input speed sensor signal - open/short)
P0720 (no output speed sensor signal - open/short)


I took this info to my dealer, to get a quote on parts and labor. Overall to replace the timing and serpentine belts, input and output sensor, would be $792 .

The timing and serpentine I will have them do, but I question the input and output sensor as I have seen them in pictures on top of the transmission. My understanding is that they are supposed to relatively accessible from under the airbox.

So my question: Should I just order the Input output sensors and do that myself? Is that portion easy enough to do ?

Any input would be greatly appreciated.

Do them yourself.Its suprisingly easy-I did mine and took me about 20 mins at most.
I was lucky enough to get both parts from the junkyar,so the whole thing cost me around 10bucks-might be worth a shot to at least try that first,and if no change buy the new ones.
heres one of the many threads on it:
http://www.hyundai-forums.com/index.php?showtopic=25073&hl=

Hope that helps

That helps quite a bit actually, I will be giving it a try myself from here, although im a bit worried about the output sensor in the "middle" . I've pretty big hands and I am concerned that I may not be able to reach it. We will see. I will post my results.

Do you know if the sensors are the same all the way up to 2005 ?

i believe they are specific to the followig groups,99s to 02s,03s to present.

Thats not the output sensor(I screwed up a bit during my first search)
Heres where each is located:
(All require a 10mm socket unless noted)
Output-under airbox,remove the 4 bolts holding the airbox.Its relativey small,and of the two is the one thats closer to the front bumper.

Input-Behind the output,stuck under a cable.The cable has 2 12mm bolts holding it on,remove these and hold the cable aside.Remove the iput same as output.

TPS(If the other two dont help) Right behind the throttle body(large metal part the airduct connect to closer to the windshield if you arent sure) Not too sure on the bolts,pretty sure its 2 10mm ones.

Makes sure when you plan on doing this,you disconnect the battery and pump the brakes to relaese left over energy.After all the rapirs are done,get the cel code cleared,and you should be set