QuestionTo Campstall. 6 cyl, 4.0 67000 miles. My wife went to Auto Zone in NJ and bring this reading;
TROUBLESHOOTING P0720
Definition - Low output speed sensor speed above 15 mph
Explanation - Vehicle speed above15 MPH while transmission output shaft speed below 60 RPM
Probable causes - 1.-Failed output shaft speed sensor
2.-Electrical problem
I have friend, 20 yrs experienced buss mechanic and European auto mechanic H.S. graduate. Understand English a little. Want to help me locate the problem. First he change $30 gas filter which did not solve the problem. Now he wants to change all that belong to tune up because was never changed. He say we will change everything until we find the problem. I don't like this way of expensive thinking an I am looking for better suggestion, perhaps from you. As for changing, as machinery mechanic I think I am able to change some things myself except that car owner manual is very poor and it dose not say or show where parts like sensors and oders are located. I also can not find anything on Internet where it would show location of shaft speed sensor, how it look like, how to repair it or change. Can you please help me diagnose "check engine" problem and give me some links so I will at list learn how those unknown parts in our car look like, their purpose and where they are?! Is very hard to maintain any car wondering what the heck now they put in your car. Also Kevin, car have alarm - I just don't want to do anything to screw it.
AnswerMario,
I feel you're on the right track with the failed output shaft speed sensor.
However, based on your information I tend to agree with the mechanic on getting the basics of the tune-up done in order to properly diagnose the vehicle. Some discrepancies on vehicles can be caused by simple problems, i.e., worn plugs, plug wires, clogged fuel filters, worn distributor cap/rotor, etc.
The output shaft speed sensor should be located on the transmission.
