Turn engine off then restart it may run ok for awhile
P0122 - OBD-II Trouble Code
Our automotive experts have put together the following information about the P0122 diagnostic trouble code. We've provided the common symptoms that occur when this code is set along with the frequent repairs that address the issues related to the P0122 code.
OBD II Fault Code
Fault Code Definition
What Does Mean?
The Throttle Position Sensor/Switch is located on the Throttle Body of the Intake Manifold and the Pedal Position Sensor/Switch is part of the Accelerator Pedal assembly. These sensors provide precise input from the driver's foot in terms of how MUCH power is needed from the engine and, how URGENTLY power is needed. As the Throttle Position Sensor is rotated from its base resting position to full acceleration, typically, it sends an increasing voltage signal to the Powertrain Control Module (PCM). This increasing or decreasing voltage signal is used by the PCM to manage the Air Fuel Ratio and Spark Timing of the engine as well as other Emissions System Components.
Code P0122 triggers when the Throttle/Pedal Sensor/Switch "A" Circuit has low output
Symptoms
Common Problems That Trigger the P0122 Code
Common Misdiagnoses
Polluting Gases Expelled
P0122 Diagnostic Theory for Shops and Technicians
When diagnosing a P0122 code, it is important to record the freeze frame information and then to duplicate the code setting conditions with a test drive while paying close attention to engine load, Mass Air Flow grams per second, RPM, and road speed on a data streaming scan tool. As you drive the vehicle, compare these values to the Throttle/Pedal Position Sensor PID or parameter ID. The Throttle/Pedal Position Sensor voltage values should rise and fall with changes in engine RPM and engine load.
Check the Throttle/Pedal Position Sensor connector with the key on-engine off. There needs to be a steady 5 volt reference voltage and an excellent ground. Find and use the proper engine performance wiring diagram to discern the proper color and position of these wires in the connector.
It is vital to do a key on-engine off test of the Throttle/Pedal Position Sensor by testing the Throttle Position/Pedal Position output from its signal wire. Typically, I operate the Throttle or Pedal manually and watch the rise and fall of its voltage or HTz on a lab scope to see if there are any sensor 'flat spots' or glitches. I test it again and watch the output on a data streaming scan tool to validate the sensor and Electronic Throttle Module(if equipped) connectivity with the PCM.
P0122 is TPS signal low, which could mean you have a bad TPS, or a fault in the wiring or connector. I suspect a bad Throttle Position Sensor.
Testimonial: "have changed TPS 4 times over last 12 mos.seems to help for a while subaru mechanic said alternator not putting out enough amps i changed it and battery which didnt help.I will check wiring. Thanks anyway"
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