Code P0122

MARK COOPER

MEMBER
1995 FORD MUSTANG
3.8L
V6
2WD
AUTOMATIC
225,000 MILES

I have the car listed above that seems to be displaying all the symptoms of a faulty TPS - faulty shifting, not wanting to shift into last gear, rough idle, and code 0122 letting me know that the voltage is low on my TPS. I have replaced the sensor as well as the connector. I have tested the front of the connector as well as back-probed the wires. My ground and ref wires are solid. My sig wire is showing a voltage of.001-.003. I traced the wire to where it starts in the harness and tested a spot there with the same results. Besides a faulty PCM, could I test anything else?

Monday, April 9th, 2018 AT 5:40 PM

2 Replies

CARADIODOC

MECHANIC
34,206 POSTS

Your voltage reading agrees with the fault code. The acceptable range of signal voltage is approximately 0.5 to 4.5 volts. Anything outside that range is what triggers a fault code.

Check for 5.0 volts on one of the wires in the plug to the TPS. If that is missing, the best suspect is a break in that wire going back to a splice. That 5.0 volt source feeds a lot of stuff. It is not likely to be missing from the computer because that would set fault codes for other sensors too.

Be careful when back-probing the connector terminals to not spread them. That will cause an intermittent connection in the future. Let me know what you find.

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Monday, April 9th, 2018 AT 6:23 PM

HARRY P

MECHANIC
2,292 POSTS

Also be sure that you installed the sensor correctly. Most TPSs have an arm on them that has to be caught by an arm inside the throttle body. If it is not caught correctly, it could trigger a low voltage reading, and P0122 code. Good luck.

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Tuesday, April 10th, 2018 AT 3:47 AM