MaxedOutSS99

My car is throwing this code P0121- Throttle Position Sensor. what exactly causes this code to go on? and how can I fix it, if I can?
thanks

Mid-Life Speed

The TPS sensor is a potentiometer that varies a reference voltage depending on the throttle position (angle). The PCM compares the measured voltage (throttle angle) with a predicted position, predicted from MAP and engine speed info. If the measured position doesn't agree with the predicted predicted, the code sets.

Did you have any other codes set ? Look for any MAP codes. Also look for a P1635 (means the reference voltage to the TPS is bad) or a P1404 (EGR code ... EGR circuit uses the same reference).

Check the wiring to the TPS and the MAP. Check the voltage at the TPS on the dark blue wire (connector pin C) with the engine off and the key in the run position. The voltage should vary between 0.6 volts at closed to above 4.0(typically 4.6 - 4.8 volts) at WOT.

MaxedOutSS99

No, thats the only code that it gave me. Ill check it again just to make sure though but just incase if it is only that. Ill post all the stuff that showed up with that code. It said it failed a test or something. But im pretty sure that was the only code that came up.

MaxedOutSS99

so the SES light went away. It was on for 2 days and now its been gone since then........ pretty weird.

Nickn20

hi i was searching and found this thread i am also throwing code P0121 and code P1635 so i checked the TPS voltage TB closed it reads .95v and full open its 5.05 volts what does that mean?

if it means anything I have removed my AC pressure, and EGR.

Mid-Life Speed

Sounds like you might have a bad ground connection .... Check the ground connections to the chassis on both wheel wells (wire lugs on studs). Also check your battery ground connection. The voltage at WOT should not go over 5 volts ... this will also set the DTC. If it is over 5 volts the ground side of the circuit may not be solid, or you may have a pb in the wiring harness to the PCM since the PCM delivers the reference voltage.

Mid-Life Speed

Sounds like you might have a bad ground connection .... Check the ground connections to the chassis on both wheel wells (wire lugs on studs). Also check your battery ground connection. The voltage at WOT should not go over 5 volts ... this will also set the DTC. If it is over 5 volts the ground side of the circuit may not be solid, or you may have a pb in the wiring harness to the PCM since the PCM delivers the reference voltage. The code P1635 could also be set because the EGR has been removed.

Sorry about the stupid double posts ... got impatient with the browser ...