Error Code P2135 is defined as Throttle/Pedal Position Sensor/Switch A / B Voltage Correlation.

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.


Error Code P2135 means the PCM (powertrain control module, also known as ECM or engine control module in other vehicle makes) has determined an erratic and incorrect reading of the voltages transmitted by the TP (Throttle Position) A or B, accelerator pedal position sensor, and actual throttle plate.

The PCM expects both the TP sensor outputs to stay within coherent and close range of one another; the PCM will regularly compare the sensor readings as a way to test the efficiency and punctuality. Each TP sensor will send signal voltage to the PCM in correlation to the position of the throttle plate. The PCM will read this signal as how far the throttle plate is open. If on TP sensor is reading at half throttle and the other is reading at full throttle, the PCM will then set the Error Code P2135, because the voltage readings will be remote and impossible for the data to be accurate.

The TP sensor is located on the throttle body inlet. P2135 means the voltage reading produced from the TP sensor and accelerator position sensor are far from each other, which means it’s inaccurate. The signal from each TP sensor and the accelerator position sensor must correlate to each other, or the code will be set.

Similar error codes are:

  • Error Code P2136
  • Error Code P2137
  • Error Code P2138
  • Error Code P2139
  • Error Code P2140

Diagnostics for these codes will the same.

Common Symptoms

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

  • Surge or hesitation when accelerating
  • Revving of engine when gas pedal is not pressed
  • RPM is higher than normal
  • Stalling
  • Sudden loss of power at cruise speed
  • Stuck throttle at current RPM

Possible Causes

In many cases, the most common of this code is the poor connection in the wiring connector or “pigtail” on the throttle body. The female terminals on the pigtail corrode or pull out of the connector. Other possible causes include:

  • Bare wire of pig-tail shorting to ground
  • Distorted top cover of throttle body, preventing gas from turning properly
  • Defective throttle body
  • Failed accelerator pedal sensor or wiring
  • Defective PCM
  • Defective TP sensor
  • Disruption in the TP sensor circuit (corrosion, open, or short)
  • Disruption in the Accelerator Pedal Position sensor circuit (corrosion, poor electrical connection, damaged wiring, short, or broken electrical connections)

How to Check

To diagnose for this code, mechanics back probe the accelerator pedal position sensor and the TP sensor using a scan tool or a multimeter to view the voltage output of each sensor. The voltage must be within the specifications set by the manufacturer.

They will also use the multimeter to test the ohm levels of the accelerator pedal position sensor and the TP sensor. Readings must be within the manufacturer’s specifications as well.

In most cases, mechanics use the TSB (Technical Service Bulletins) and recalls related to some makes and models for this code. They will also compare the make and model of the vehicle to its applicable recalls and TSBs to determine if there is one that has been implemented.

They will check online or in the service manual for possible relearn procedure to reset the computer.

If additional codes are present, these other codes must be addressed first since they are components in the system, and may be the direct cause of the P2135.

Technicians will check the connectors and terminals for signs of damages, such as corrosion.

They will also check the top cover of the throttle body for cracks or warping.

How to Fix

Replacement of one or both TP sensors

Replacement of the accelerator pedal position sensor

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

Error code P2135 may cause the vehicle to stall, which can be dangerous if it happens when you’re going through turns or in heavy traffic. Thus, this code must be addressed as soon as possible.