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P2122 Code – What Does It Mean & How To Fix It

This is one of the most frequent OBD2 trouble codes. Read the full article below to know what it means, how to fix it, and what other codes may show related to it.


OBD II error code P2122 is a general code that is defined as “Throttle Position Sensor (TPS) or Switch “D” Circuit Low


The P2122 trouble code log means that a low voltage is detected at the TPS and is set when the Powertrain Control Module (PCM) detects an abnormally low input voltage from the sensor or circuit in the throttle control system that is marked as “D”. 

Depending on the make and model of the vehicle, this detection can trigger a forced shutdown of the engine, a forced idle speed, or a forced reduction in power output to avoid overloading the circuit.


Although the P2122 trouble code log has many potential causes, majorly it can be due to one of four components

  • Faulty throttle position sensor
  • Defective throttle actuator control motor
  • Failure of position actuator, or the pedal position sensor

Damaged wiring, connectors, or grounds.


Below mentioned are the common symptoms related to OBD error code P2122

  • Check Engine Light ON
  • Black smoke when the engine starts
  • Misfiring
  • Strong acceleration
  • Engine Stalling
  • No-start condition


For the correct diagnosis and solution of the error code P2122, you should follow the steps mentioned beneath

  • Use an OBD-II scanner to get the entirety of the trouble codes that are set aside by the PCM. Qualified technicians can collect vehicle performance data and report any abnormalities in the form of OBDII fault codes by using special scan tools.
  • Once the scan has been performed and recorded the P2122 code, further testing and inspections are needed to identify potential issues.
  • Visually inspect all the wiring and connectors. If damaged cables or connectors are found, replace them. The mechanic then clears the fault code from the computer’s memory and uses the special scan tool again. 
  • If the P2122 code is not registered, the problem can be resolved. On the other hand, if the code is re-registered, additional diagnostic work is required.
  • Use a digital volt / ohmmeter to verify voltage readings across the throttle position sensor, throttle actuator control motor, throttle position actuator, and pedal position sensor. 
  • Determine if any of these components are the source of the low voltage discovered by the on-board computer, so that the faulty component can be replaced. Technicians can also check the voltage across the wiring, grounding, and Controller Area Network (CAN) bus network to repair or replace any worn or damaged parts. 
  • After the repair is complete, the mechanic will clear the OBDII trouble code, look for the exception again, and can test the vehicle to make sure the problem has been resolved.

Common mistakes

Once the P2122 code is recorded, mechanics sometimes make the following mistakes:

  • Failure to resolve the fault code in the order of occurrence, when multiple codes are recorded 
  • Failing to confirm the existence of the P2122 code
  • Do not erase the code Code P2122 after repairing On-board computer

How serious is this?

While some vehicles will not stop after registering the P2122 error code, this does not mean that the problem causing it should be ignored. Regardless of whether the root cause of the code log is a faulty component or a loose wire or other complete cause, failure to fix the problem may have an adverse effect on other components or systems. This may result in more maintenance costs and troubles than paying attention to the problem in a timely manner.

What repairs can fix the code?

Once the P2122 fault code registration is confirmed with a special scan tool, the following measures may be required:

  • Replace or relocate the ground wire
  • Replace the CAN wiring and / or bus harness Throttle Actuator Motor or Connector
  • Replace Throttle Position Sensor, Throttle Actuator Control Motor, Throttle Position Actuator, or Pedal Position Sensor

Related codes

  • P2120 – Throttle/Pedal Position Sensor/Switch “D” Circuit
  • P2121 – Throttle/Pedal Position Sensor/Switch “D” Circuit Range/Performance
  • P2123 – Throttle/Pedal Position Sensor/Switch “D” Circuit High
  • P2124 – Throttle/Pedal Position Sensor/Switch “D” Circuit Intermittent


The OBD-II scanner error code P2122 is not something that can be ignored. P2122 code unresolved for an extended period of time could cause significant damage to your engine or other components of your vehicle. If the engine lags or decelerates, the engine may run unstable and have different driving complaints, which may lead to unsafe driving conditions. Therefore, it is important to diagnose and address the potential need for multiple tests with a scan tool or voltage meter, hands-on inspections, and test drives as soon as possible.

P2122 Code – What Does It Mean & How To Fix It