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P0122 code

MartylustMartylust Member Posts: 2
edited October 2022 in Pontiac

The code is low circuit or voltage to throttle position sensor I changed the TPS I checked the voltage to it clean the throttle body and the egr valve took off the upper intake manifold I also replaced that and the gasket.. I changed the map and maf sensors I change the PCV valve and check the fuses to the ECM.. also because I was having a random misfire I did all of that and change the spark plugs coil packs and wires.. I thought the sluggishness was due to this but it had nothing to do with symptoms are pretty much you can't drive the car it doesn't go anywhere hardly gets up to 30 miles an hour apparently when this code triggers it puts the car in fail safe mode I'm wondering does anyone know is there a sensor on the accelerator pedal ?? Or does anyone have any suggestions for me any kind of help would be appreciated again it's a 2001 Grand Prix GT sedan


  • thecardoc3thecardoc3 Member Posts: 5,631
    Do you have a scan tool that allows you to see the engine data, specifically the TPS voltage? The code sets when the TPS voltage falls below .1 volts for more than 1 second. You will need to monitor the voltage either in scan data or at the TPS sensor, pin C dark blue wire and at pin 66 of connector #2 of the PCM. It's possible that the voltage is getting pulled down randomly from either a wiring issue (abrasion contacting ground) or losing the reference voltage to the sensor.

    That signal voltage going low is the only thing that causes that code.
  • MartylustMartylust Member Posts: 2

    Excellent thank you for your input !! I do have a cheap $35 scan tool I got on Amazon.. I'll see if I can pull up the live data on it see if it gives me the voltage otherwise I'll just use my multimeter like you said.. quick ollow-up question before I get into this tomorrow... Do you know if the 2001 GT has that feature where it will go into "failsafe mode" or "limp mode" when an important component or sensor goes down or isn't receiving the proper voltage ?? I've researched it a little and I haven't found any litature that says this particular model has that feature as a safety mechanism.. but the symptoms that its displaying seem to line up with that theory.. either way I'm going to do exactly what you recommended and hopefully that will send me in the right direction and allow me to finally fix this issue once and for all cuz the car's been sidelined out of commission for a couple weeks now ..what a headache.. although I'm grateful it isn't something much more serious like I originally suspected..again thank you for your input and suggestions !!

  • thecardoc3thecardoc3 Member Posts: 5,631
    It does not have a limp in strategy like a vehicle that would have an electronic throttle body, but there are some functions that will be affected by the loss of that signal. The ECM actually uses substitute values and does it's best to try and keep things functional during a failure like this.
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