After hunting down my evap leak I now have another code P0720:Speed sensor Output incorrect. This is my first vehicle with an auto and obdII so I am still getting used to all the computers. Did a search and couldn't find too much. I have cleared the code but it keeps coming back. The sensor is $80 at advance any ideas before I replace it? It is in a 1998 XJ 4.0 AW4 NP231
Thanks!

 

If you took the vehicle to you local garage and asked them to fix the problem, they would charge a minimum of $80 for the part, and at least the same amount again to fit it.

Of course, there could be some other fault causing the ODB to display this fault. Should you deduce that no serious harm will occur driving with this fault, the engine warning light may be illuminated for some other reason – possibly a fault which should be addressed immediately (otherwise very expensive damage will result). This is the risk you run, driving around with your engine warning light on.

 

Test the circuit for the output speed sensor before you replace it. Unplug the sensor and with a multi meter test the resistance across the two pins on the sensor, if resistance is higher than 800 ohms replace the sensor. Also before you cancel out the thought. The dealer ships are doing their utmost to bring in customers, with that said this sensor would more than likely be cheaper and more correct to fit if you priced it out at the dealer parts counter. Not all aftermarket "direct fit" replacement parts are made to the exact OEM specs.