Error Code P2123 is defined as Throttle/Pedal Position Sensor/Switch D Circuit High Input, an issue usually caused by wiring short positive, APP/TPP/ sensor or switch problems.

This error code is a generic trouble code, meaning it applies to all vehicles equipped with OBD-II system, especially those made since 1996 up to present. Specifications on the definition, troubleshooting, and repairs, of course, vary from one make and model to another. However, it only applies to vehicles with an electronic throttle body.


Error Code P2123 indicates that the PCM (powertrain control module, also known as ECM or engine control module, which in charge of receiving signals from the throttle position (TP) sensor) has determined a malfunction in one of the circuits of the TP sensor.

Common Symptoms

As with other error codes, this code activates the Check Engine light and registers the code to the vehicle’s memory. Other obvious symptoms include:

  • Stalling
  • No start condition
  • Poor acceleration

Possible Causes

Since this code only applies to vehicles equipped with an electronic throttle body, possible causes would be:

  • Faulty throttle body motor
  • Damaged to the connector or wiring connected to the throttle body motor
  • Faulty throttle position sensor
  • Faulty PCM (rare)

How to Check

To diagnose this code, mechanics start by locating the throttle body of the vehicle to check its connectors and wirings that lead to the throttle body motor and throttle position (TP) sensor.

If all the connectors and wirings look good, the mechanic will proceed to test the TP sensor and the throttle body motor for the proper function using the recommended procedure set by the vehicle’s manufacturer.

In the unlikely event that problem could not be found after the test, the mechanic would then proceed to test the PCM to make sure it is working properly.

Whichever part is found to be defective would be replaced at the vehicle owner’s request.

How to Fix

Repairs for this code are pretty simple and straightforward, which of course can only be determined through thorough diagnosis. Some of the common repairs are:

  • Replacement of the throttle body assembly or the throttle body motor
  • Repair or replacement of the wirings connected to the throttle body motor
  • Replacement of the TP sensor
  • Repair or replacement of the wiring associated with the TP sensor
  • Replacement of the PCM

Error Code P2123 is a serious problem as it can cause driveability conditions, such as poor acceleration or even no start condition. In worst cases, the code can cause stalling, leaving the driver stranded on the road. Thus, it is important to have this code thoroughly diagnosed and repaired as soon as possible.