Help!!! DTC P0121 Error ???
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Joined: Mar 2001
Posts: 141
Help!!! DTC P0121 Error ???
Intermintently I am getting a P0121 error which says (according to the AutoZone Scanner) Pedal Position Sensor perf error. I called GM Parts places and they said we do not have Pedal Position Sensors in our cars.
I have since replaced the Throttle position sensor (Which could have also thrown this code) and measured my IAC counts, everything looks good, but I still have the SES light and my car shifts horribly.
I found the following on a Bullit mustang site:
http://www.bullittarchive.com/reference/DTC/
It explains what the error is and how it is tested. Has anyone had this error? or have a clue on how I can fix it.
Does anyone have a service manual that would help troubleshoot this?
Thanks in advance!
I have since replaced the Throttle position sensor (Which could have also thrown this code) and measured my IAC counts, everything looks good, but I still have the SES light and my car shifts horribly.
I found the following on a Bullit mustang site:
http://www.bullittarchive.com/reference/DTC/
It explains what the error is and how it is tested. Has anyone had this error? or have a clue on how I can fix it.
Does anyone have a service manual that would help troubleshoot this?
Thanks in advance!
Registered User
Joined: Feb 2000
Posts: 607
From: Casselberry FL USA
Pasted from a LS1Tech.com thread:
LS1.com and LS1tech.com are good places to search for the diagnostic code issues.
HTH
P0121 sets when the predicted throttle angle does not match the actual throttle angle.
P0122 sets when the TP sensor signal voltage is less than 0.2 volts.
It sounds like you have a wiring problem ( broken wire somewhere). You can count on this low voltage being lower than normal closed throttle voltage. A bad ground would increase sensor output so rule that out. It is possible that your 5 volt reference voltage took a dive so carefully inspect the wiring to the sensor. To save weight, the wiring is smaller and is more prone to breaking inside the insulation. The telltale signs of internal breakage would be a bubble in the wiring insulation. You could also have had a loss of 5 volt reference from the PCM. If so, you would expect DTCs from other sensors using the same 5 volt reference. Usually this is an EGR DTC.
P0122 sets when the TP sensor signal voltage is less than 0.2 volts.
It sounds like you have a wiring problem ( broken wire somewhere). You can count on this low voltage being lower than normal closed throttle voltage. A bad ground would increase sensor output so rule that out. It is possible that your 5 volt reference voltage took a dive so carefully inspect the wiring to the sensor. To save weight, the wiring is smaller and is more prone to breaking inside the insulation. The telltale signs of internal breakage would be a bubble in the wiring insulation. You could also have had a loss of 5 volt reference from the PCM. If so, you would expect DTCs from other sensors using the same 5 volt reference. Usually this is an EGR DTC.
HTH
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