P1720 output shaft speed sensor
 

Good morning. 98 gt automatic. I recently got the code P0720 after noticing that the od off button was flashing and the check engine light came on. I switched out the part from oreillys and I still get the flashing light. Is there anything else that might cause that code? Or does ir have to drive a few miles for the computer to recognize the new part? Thx Gordon

Assuming you replaced the correct sensor. And the problem persists, next step would be to check the harness and main connector for issues. If there is an internal problem in the trans throwing the 720 code you'd most likely have other transmission codes associated with it

Thank you. I have checked all the connections and everything seems to be ok. Could a bad alternator cause that part to not work correctly?

I put on another alternator and the OD light still flashes. Is there a particular way you have to put a new speed sensor in other than taking the old one out and putting the new one back the same way?

see post #2, you either have a wiring issue or an internal transmission issue. Are you sure that is the only code the car is throwing? is it shifting hard?

Yes. Code reader only showing one code read. I`ll check the wiring again. I really appreciate your help with this

What are the chances that it could be as simple as transmission fluid?

not a fluid issue. and a cheap scanner will most likely not be able to pull all the codes. there may not be any more codes....however if the wiring is all intact and allow continuity, you could have an internal transmission issue.