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P0122 OBD-II Trouble Code: Throttle Pedal Position Sensor/Switch (TPS) A Circuit Low Input

Check Engine Light

P0122 code definition

Throttle Pedal Position Sensor/Switch (TPS) A Circuit Low Input

What the P0122 code means

The P0122 is the generic OBD-II code which indicates that the Engine Control Module (ECM) has seen the TPS sensor circuit A output voltage go below the sensor's expected range.

What causes the P0122 code?

The TPS sensor circuit A output to the ECM went below the specified voltage and is going to .2 volts or less.

What are the symptoms of the P0122 code?

  • The ECM turns the Check Engine Light on and goes into a failsafe mode by cutting current to the throttle actuator to put the throttle valve to approximately less than a 6 degrees opening.

  • The ECM controls fuel injection and timing to control engine speeds.

  • The vehicle would be able to be driven very slowly with limited throttle response.

  • The engine may idle higher than normal and not accelerate as well as before it started to fail.

Note: The symptoms are determined by the manufacturer failsafe ECM strategy for the vehicle during a failure and may vary between manufacturers and vehicles.

How does a mechanic diagnose the P0122 code?

  • Scans and documents the codes received, and views the freeze frame data to see when the code was set

  • Clears the OBD-II fault codes and retests the vehicle to see if the code comes back

  • Visually checks all the TPS connections and wiring for any loose or damaged items

  • Compares the data between TPS circuit A and B on the scanner and if incorrect, performs the TPS pinpoint tests as per the manufacturer's recommendations

  • Replaces the TPS if necessary, clears the codes, then performs a road test

Common mistakes when diagnosing the P0122 code

  • Not doing a visual inspection first

  • Not scanning, documenting, clearing and retesting the codes to verify failures

  • Replacing the TPS sensor without and indication that it is the problem

  • Not comparing the TPS sensor A and B to be within specification before and after repair or replacements

How serious is the P0122 code?

The P0122 code will cause the engine's ECM to go into a failsafe mode, which will cause various drive issues like lack of acceleration, high idle, bucking or jerking, limited speeds, or stalling, depending on manufacturer failsafe mode strategy.

What repairs can fix the P0122 code?

Additional comments for consideration regarding the P0122 code

  • The P0122 code may be accompanied by other TPS codes, so following the manufacturer's pinpoint tests for each code received may be needed to fix the complaint.

  • Most failures for code P0122 involve a defective TPS sensor, or a loose connector.

  • All TPS codes will cause the ECM to go into failure mode; drive symptoms will be the roughly the same.

Need help with a P0122 code?

YourMechanic offers certified mobile mechanics who will come to your home or office to diagnose and repair your vehicle. Get a quote and book an appointment online or speak to a service advisor at 1-800-701-6230.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details

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