P2139 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch D / F Voltage Correlation

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Cost of diagnosing the P2139 code

P2139 is a diagnostic trouble code (DTC) for "Throttle/Pedal Position Sensor/Switch D / F Voltage Correlation". This can happen for multiple reasons and a mechanic needs to diagnose the specific cause for this code to be triggered in your situation. Our certified mobile mechanics can come to your home or office to perform the Check Engine Light diagnostic. Once we are able to diagnose the problem, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. All our repairs are backed by our 12-month / 12,000-mile warranty.

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P2129 code definition

Throttle/Pedal Position Sensor/Switch D / F Voltage Correlation

What the P2129 code means

The P2129 code means that an improper voltage correlation between the throttle and pedal position sensors has caused the throttle plate to become unable to open and close properly. The electronic control unit (ECU) uses the signals from both the throttle position sensor and the pedal position switch to determine how much to open or close the throttle plate. When the malfunction between the two signals is found, the P2129 code is set. Along with this code, the Check Engine Light is illuminated and a failsafe mode set. The failsafe mode will remain until the code is repaired or normal operation resumes.

What causes the P2129 code?

  • Failed electronic throttle body
  • Pedal position sensor failure
  • Faulty throttle position sensor
  • Open or short in the wiring harness
  • Poor electrical connection

What are the symptoms of the P2129 code?

  • Check Engine Light
  • No acceleration at all
  • Engine stalling when coming to a stop
  • Lack of power
  • Throttle stuck open

The symptoms can vary greatly with the P2129 code

How does a mechanic diagnose the P2129 code?

  • Hooks up a scan tool to the ECU and checks for any codes stored, including history and pending codes

  • Notes all codes as well as any freeze frame data available

  • Clears the codes and then performs a test drive, preferably under similar conditions to the freeze frame data

  • Performs a visual inspection, looking for any obvious signs of failure

If nothing obvious is seen during the visual inspection, then the technician will use a multimeter to check for the presence of voltage at the throttle body, as well as at the pedal position sensor.

If voltage is found, than the air intake will be removed and the throttle plate inspected for the ability to function properly at all.

Common mistakes when diagnosing the P2129 code

A common mistake is assuming that the throttle plate is actually opening and that one of the sensors must be the cause. The throttle plate can become stuck with carbon causing the plate to not open or close which makes the throttle position sensor read faulty.

How serious is the P2129 code?

The P2129 code is serious. It can cause the vehicle to not be able to move or die while running. Extreme caution should be taken with this code and if any driveability problems are found the vehicle should not be driven and needs to be repaired immediately.

What repairs can fix the P2129 code?

  • Replacing the throttle position sensor
  • Replacing the electronic throttle body
  • Replacing the pedal position sensor
  • Repairing or replacing the wiring harness
  • Resolving electrical connection faults

Additional comments for consideration regarding the P2129 code

In some cases, the throttle may not operate because it has become stuck. This happens when excessive amounts of carbon build up and bind the throttle plate linkage. In these cases throttle body cleaner can be used to remove the carbon carefully, which may restore the throttle to proper operation.

Need help with a P2129 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 1-800-701-6220.

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