Fault code P2138 – throttle/pedal position sensor/switch “D”/”E” voltage correlation

Fault code P2138 is called “Throttle/Pedal Position Sensor/Switch (TPPS) “D”/”E” Voltage Correlation” but in different programs it may be called differently. This fault designation applies to all vehicles equipped with OBD-II.

Technical description and explained code P2138

Vehicle Code P2138 “Throttle position or accelerator pedal voltage correlation error “D”/”E”. Indicates a problem with the ability of the throttle valve to open and close properly.

Fault code P2138 – throttle/pedal position sensor/switch

Throttle control technology began to be widely adopted in the 1990s. Its mission, to provide greater control over emissions, fuel economy, traction and stability control, cruise control, and transmission response.

Prior to that, the vehicle’s throttle was controlled by a simple cable with a direct connection between the gas pedal and the throttle. The throttle position sensor (TPS) is located opposite the throttle connection.

The TPS converts throttle movement and position into a voltage signal and sends it to the engine control computer. Which uses the alternating voltage signal to form an engine control strategy.

Electronic throttle control technology consists of an accelerator pedal position sensor, an electronically controlled throttle valve. As well as two integrated throttle position sensors for correlation ratios and an engine control computer.

The computer monitors the ratio of both voltages. When both voltages match, the system runs normally. When they deviate by two seconds, code P2138 is set, indicating a fault somewhere in the system.

Other fault codes may be present with this error, which further defines the problem. It should be understood that loss of throttle control can be dangerous.

Symptoms of vehicle malfunctions

The main signal that an error P2138 has occurred is the Malfunction Indicator Lamp (MIL) is also known as the CheckEngine Light.

It can also be warning signs such as:

  1. The “Check engine” control lamp on the control panel will light up (the code will be stored as a fault).
  2. Other related trouble codes may also be present.
  3. The engine jerks/misses the ignition at idle or under load.
  4. Engine stalls or starts poorly.
  5. Engine cannot be accelerated, throttle response is unresponsive.
  6. Bad acceleration.
  7. Engine power drop due to slow throttle response.

The error P2138 is quite serious, as its occurrence may cause problems with the engine and vehicle controllability. In order to avoid dangerous situations on the road, it is recommended to eliminate this error as soon as possible.

Factors that can cause this error code

The error code P2138 can mean that one or more of the following problems have occurred:

  • Throttle position sensor or accelerator pedal position sensor (TPPS) failure.
  • Throttle position sensor circuit failure or bad electrical connection.
  • Throttle position sensor wire harness is shorted to ground or other wire.
  • Throttle body cover is deformed, preventing proper rotation of gears.
  • Electronic throttle body is defective.
  • Corrosion of MAP or TPS connector.
  • Jammed throttle return spring.
  • Sometimes the cause is a defective PCM module.

How to fix or reset OBD-2 code P2138

Some suggested steps for troubleshooting and fix the error code P2138:

  1. Read all stored data and error codes with an OBD-II scan tool. To find out when and under what circumstances error P2138 appeared.
  2. Clear the error codes from the computer memory and test-drive the vehicle to find out if the fault appears again.
  3. Visually inspect the electrical wiring and connections related to the “D” and “E” throttle position sensors for looseness and damage.
  4. Compare “D” and “E” throttle position sensors using a scan tool and replace faulty sensor if necessary.
  5. Check for proper operation of the return spring.
  6. Clear error code from computer memory again, test drive vehicle to see if problem is resolved.

Diagnose and repair of problems

Carefully check the throttle position sensor (TPS), wiring connector, and wiring for breaks, etc. Repair or replace if necessary to clear error P2138.

Check throttle position sensor (TPS) voltage, it should be between 0.45-0.17 volts (some vehicles may have different values). If the voltage is too low or too high, this indicates a problem. Replace the sensor if necessary.

If recently replaced, you may need to adjust the TPS. On some vehicles, the installation instructions require the sensor to be properly adjusted or taught.

Inspect the upper throttle body cover for cracks or deformation. If present, replace the throttle body.

Use a voltmeter to check the accelerator pedal sensor (APP). Turn the key on and slowly depress the pedal. The voltage should increase smoothly from 0.5 to 5.0. Replace the sensor if the voltage is constantly high or there is simply no voltage on the signal wire.

If there are no symptoms, the problem may be intermittent, and clearing the code may solve it temporarily. If this is the case, you should definitely check the wiring to make sure it is not chafing or frayed anywhere, etc.

On which vehicles does this problem occur most frequently

Fault code P2138 can occur on different vehicles but there are statistics on which brands this occurs most often. Here is a list of some of them:

  • Acura (TL)
  • Audi (A4)
  • Cadillac (Escalade)
  • Chery
  • Chevrolet (Aveo, Captiva, Cruze, Epica, Impala, Silverado, TrailBlazer)
  • Dodge (Caliber)
  • Ford (Focus, Fusion, Transit)
  • Geely (Emgrand X7)
  • Honda (Accord, Pilot)
  • Hyundai (ix35)
  • Infiniti
  • Kia (Ceed, Rio, Sorento, Sportage)
  • Lifan (X60)
  • Mazda (3, 6)
  • Mercedes-Benz
  • Mitsubishi (Grandis, L200, Outlander)
  • Nissan (Almera, Juke, Maxima, Note, Qashqai, Teana, Tiida, Titan, Versa, X-Trail)
  • Opel (Antara, Astra, Corsa, Insignia)
  • Pontiac (G6, Grand Prix GXP)
  • Skoda (Octavia)
  • Subaru (Legacy)
  • Toyota
  • Volkswagen (Golf, Tiguan)
  • Vortex (Estina)
  • GAZelle (Business)
  • LADA (Granta, Kalina, Largus, Niva, Priora)
  • UAZ (Patriot)
  • VAZ (2114)

Fault code P2138 can sometimes be found with other errors. The most common are the following: P0068, P0120, P0121, P0122, P0123, P0124, P0134, P0137, P0223, P0300, P0302, P0306, P0504, P0510, P1125, P2106, P2121, P2122, P2123, P2125, P2127, P2135, P2136, P2137, P2139, P2140, P2251.

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