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P0639 OBD-II Trouble Code: P0639 Throttle Actuator Control Range/Performance (Bank 2)

diagnostic check engine light

P0639 code definition

A P0630 trouble code is stored when the Powertrain Control Module (PCM) or one of the other control modules has detected a fault in the throttle actuator control in bank 2 of the engine, which refers to the bank in the engine not containing the number one cylinder. Other control modules that might detect this fault include the alternate fuel control module, the anti-theft module, the antilock brake control module, the body control module, the climate control module, the cruise control module, the fuel injection control module, the instrument panel control module, the proximity alert module, the traction control module, and the turbo control module. In addition to a P0639 trouble code, the PCM might also store a P0638 code.

What the P0639 code means

The storage of a P0639 trouble code means that the throttle actuator control has encountered an error. While the storage of this code usually results in the illumination of the Check Engine light, some vehicle models require multiple drive cycles, up to eight, with a failure for the Check Engine light to come on.

What causes the P0639 code?

A defective throttle actuator control, throttle position actuator, or throttle position sensor can cause the storage of a P0639 trouble code. In addition, faulty wiring or connectors within the Control Area Network (CAN) Bus harness or a loose ground strap or broken ground wire within one of the control modules can cause storage of this code. A final cause is a defective CAN Bus harness.

What are the symptoms of the P0639 code?

Symptoms of a P0639 trouble code is a failure for the vehicle to start, misfires while idling, and stalling. Additional symptoms include black smoke issuing from the exhaust when starting the vehicle and poor acceleration.

How does a mechanic diagnose the P0639 code?

To diagnose a P0639 trouble code, a mechanic needs an advanced scanner, a digital volt/ohm meter, a specialized scanner, and a CAN Bus system wiring diagram. When they have gathered the necessary equipment, the mechanic should perform the following steps:

  • Carefully perform a visual inspection of all wiring, connectors, and components associated with the throttle actuator control.
  • Clear the trouble code and retest the system after repairs to make sure that they were successful.
  • If the wiring, connectors, and other components appear normal and the code persists, download the freeze frame data and all stored codes for further analysis.
  • Clear the code and test drive the vehicle to test for an intermittent condition. Keep in mind that a P0639 trouble code is only found in vehicles with an electronically controlled throttle body.
  • The mechanic should also test the voltage between the throttle actuator control motor connector and the PCM.
  • If the mechanic does not detect voltage or a ground signal, they should disconnect the PCM and all related control modules from the connector and test each individual circuit for resistance and continuity.
  • If the mechanic detects a voltage and ground signal at the throttle actuator motor connector, the should assume a faulty motor.
  • After the necessary repairs are made, the mechanic should clear the code and test drive the vehicle to see if the code returns.
  • If the code persists, the mechanic should use a specialized scanner and a CAN Bus system wiring diagram to check the pins of the CAN Bus harness. The mechanic should also install a memory-saving device to prevent PCM and control module memory loss.
  • The mechanic should compare their findings to the manufacturer's specifications, making sure to test the continuity of the control module ground circuits with the battery ground using an auxiliary ground cable to help diagnose any system ground inconsistencies.
  • The mechanic should also test continuity between each individual control module connectors with the digital volt/ohm meter, comparing what they get with the manufacturer's specifications.
  • After making all of the necessary repairs, the mechanic should clear the P0639 trouble code and retest the system to see if the code returns.

Common mistakes when diagnosing the P0639 code

Most mistakes made by mechanics in relation to a P0639 trouble code include treating the symptoms and codes stored in reaction to the code storage. A mechanic can best treat a P0639 trouble code by downloading the freeze frame data and treating the codes in the order they were stored.

How serious is the P0639 code?

While a vehicle can still operate with a P0639 trouble code, it is best to diagnose and treat a P0639 trouble code as soon as possible to avoid the no-start or stalling condition that can accompany it.

What repairs can fix the P0639 code?

To fix and clear a P0639 trouble code, a mechanic must perform the following repairs:

Need help with a P0639 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 1-800-701-6230.

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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