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P2127 – What Does It Mean and 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.

Definition

P2127 is an OBD-II Code that refers to Throttle Position Sensor E Circuit Low Input

Meaning

A P2127 code is a general diagnostic trouble code that occurs when the PCM/ECM detects that the throttle or pedal position sensor switch E has a low input. The pedal position sensor is a pressure-sensitive device located on the gas pedal. that the ECU when the gas pedal is depressed and how far it is depressed. 

When the ECU detects a low input from the pedal, the Check Engine Light illuminates and the P2127 code is stored in the ECU.

Causes

Common causes for this code include:

  • Damaged, burnt, shorted, disconnected, or corroded wiring and/or connectors 
  • Bad pedal position sensor
  • Faulty throttle plate position sensor
  • Malfunctioning throttle actuator motor
  • Failed or failing PCM (Rare)

Symptoms

The symptoms of a P2127 code are:

  • Illuminated Check Engine Light
  • Surging
  • Stalling
  • Rough idle
  • Bad or no acceleration
  • Reduced engine performance
  • The engine might go into limp mode while driving

Diagnosis

To diagnose a P2127 DTC code, a technician would:

  1. Scan for codes in the ECM and look at the freeze frame data for failure.
  2. Visually inspect the wiring and connectors for damage, burnt wiring, shorts, etc.
  3. Test the pedal position sensor for proper function.
  4. Test the throttle plate position sensor for proper function.
  5. Check for voltage at the throttle actuator motor.
  6. Check for communication between the ECM and throttle actuator motor.
  7. If all of the above tests check out, the PCM would likely need to be replaced.

Common mistakes

The following are some of the most common mistakes that a technician may make when diagnosing a P2127 code:

  • Not thoroughly inspecting all the wiring and connectors for damage.
  • Not checking for voltage at the throttle actuator motor.
  • Not checking for communication between the ECM and throttle actuator motor.
  • Failing to properly diagnose the code.

How serious is this?

A P2127 code is a low to moderate priority code. It will not cause the engine to stall, but it can cause a variety of other problems such as reduced engine performance, surging, and rough idle.

What repairs can fix the code?

The following are solutions that may fix this problem:

  • Repair or replace any wiring that is damaged
  • Check the pedal position sensor for proper function
  • Check the throttle plate position sensor for proper function
  • Replace the throttle actuator motor
  • Replace the PCM (Rare)

Related codes

A P2127 is related to and may be accompanied by the following codes:

P2126 – Throttle Position Sensor E Circuit High Input

P2119 – Throttle Actuator Control System – Range/Performance

Conclusion

In conclusion, the P2127 code is a diagnostic trouble code that refers to a problem with the throttle position sensor switch E. There are a variety of potential causes for this code, and the most common solutions are to repair or replace any damaged wiring, check the pedal position sensor for proper function, and check the throttle plate position sensor for proper function. If all of those tests check out, then the PCM may need to be replaced.