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P2135 OBD-II Trouble Code: Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation

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P2135 code definition

Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation

What the P2135 code means

This particular trouble code indicates that the Power Control Module (PCM) has detected an erroneous reading regarding the voltages transmitted by throttle position sensor A or B, the accelerator pedal position sensor and or the actual throttle plate. The PCM expects both throttle position sensor outputs to stay within a logical and fairly close range of one another. The PCM will regularly compare the sensor readings as a way to test their efficiency and punctuality. Each throttle position sensor will send the PCM a voltage signal in correlation to the position of the throttle plate. The PCM interprets this signal as how far the throttle plate is open. If one throttle position sensor is reading at half throttle and the other is reading at full throttle, the PCM will set a code P2135 because the voltage readings will be so remote that it is impossible for the data to be accurate.

The throttle position sensors will be located on the throttle body inlet. The P2135 code indicates that the voltage readings produced from the throttle position sensors and or the accelerator position sensor are so distant from each other that they must be inaccurate. The signal from each throttle position sensor and the accelerator position sensor must correlate to each other, or a code such as P2135 will set.

The throttle position sensor produces a voltage signal according the position of the throttle plate. The farther the plate is opened the higher the voltage output of the throttle position sensor will be. To keep things in perspective the accelerator position sensor operates in an identical fashion. The accelerator position sensor is near the gas pedal. It will also send a voltage signal back to the PCM according to how far the pedal is pushed down. The farther the gas pedal is pushed down, the higher the voltage signal from the accelerator position sensor to the PCM should become. The PCM expects the readings from each sensor to display similar data because they should all be under the same conditions. The accelerator pedal position sensor will tell the PCM how far the gas pedal is pushed down. The PCM will use the data and compare it to its pre programmed parameters. It will basically say “ the gas pedal is down 60% thus far so I know that the throttle plate will have to be open in equal amounts (60%):” Then the PCM will send a signal to the throttle position sensors to open them up in accordance to how far the gas pedal is pressed down. All of this happens within a fraction of a second.

If the voltage readings of the throttle position sensor and the accelerator position sensor varies too much, then a code P2135 will set.

What causes the 2135 code?

  • Faulty PCM
  • Faulty throttle position sensor(s)
  • Faulty accelerator position sensor
  • Disruption in the throttle position sensor circuit such as an open, corrosion, short, damaged wiring or broken electrical connections
  • Disruption in the accelerator pedal position sensor circuit such as an open, corrosion, poor electrical connection, short, damaged wiring or broken electrical connections

What are the symptoms of the P2135 code?

  • Surge or even possibly a hesitation when accelerating
  • Revving of the engine when gas pedal is not pressed
  • RPM’s are higher than usual
  • Check Engine Light illumination
  • Vehicle may stall out

How does a mechanic diagnose the P2135 code?

  • Back probes the accelerator pedal position sensor and throttle position sensor with a multimeter or scan tool. This allows the voltage output of each sensor to be viewed. The voltages should be within manufacturer’s specifications.

  • Uses a multimeter to test the ohm levels of the accelerator pedal position sensor and throttle position sensor. These readings should also be within manufacturer’s specifications

  • Checks TSB’s (Technical Service Bulletins) and recalls related to some makes and models for this particular code. A technician must compare the make and model of a vehicle to its applicable recalls and TSB’s to determine if there is one that has been implemented.

Common mistakes when diagnosing the P2135 code

I have heard of the throttle position sensors 1 and 2 being mixed up due to lack of knowledge, resulting in the replacement of the wrong sensor. Ensure that each sensor is distinguished properly to save time and money.

How serious is the P2135 code?

The vehicle may stall out which can be dangerous if it happens in heavy traffic or when going around turns.

What repairs can fix the P2135 code?

  • Replacing one or both throttle position sensors

  • Replacing the accelerator pedal position sensor

  • Repairing a fault in a circuit (throttle position sensor circuit, accelerator pedal position sensor circuit) such as open, short, corroded wiring, or poor connection.

Additional comments for consideration regarding the P2135 code

In some cases, no parts will need replacement and the PCM will need a flash or update. Consult with your mechanic to find out if this will apply to your particular make and model of vehicle. The information needed to determine if a vehicle will require a PCM flash or update will be found in the TSB’s history of the vehicle.

Need help with a P2135 code?

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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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