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P0638Throttle Actuator Control Range/Performance (Bank 1)

What it means

The electronic throttle doesn't move to the position the ECU commands quickly or accurately enough.

Symptoms

  • Limp mode with very low power
  • Idle problems or stalling
  • Electronic throttle warning light

Common causes

  • Dirty or sticking throttle body
  • Worn throttle motor or gears
  • Wiring fault to the motor
  • Low supply voltage

What to check first

  1. Clean the throttle body and run the relearn
  2. Compare commanded and actual throttle angle
  3. Check the motor wiring and supply
Can I drive with P0638? Not recommended. P0638 can lead to stalling, limp mode or engine damage; diagnose it before driving further.

Generic OBD-II meaning. Manufacturer-specific meanings and checks can differ; always check the service information for the car.

How to test the parts behind P0638

Throttle and accelerator pedal position sensorsWiring, typical values, multimeter and scope tests

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P0638: questions and answers

What does P0638 mean?

P0638: Throttle Actuator Control Range/Performance (Bank 1). The electronic throttle doesn't move to the position the ECU commands quickly or accurately enough.

What are the symptoms of P0638?

Limp mode with very low power. Idle problems or stalling. Electronic throttle warning light.

What causes P0638?

Dirty or sticking throttle body. Worn throttle motor or gears. Wiring fault to the motor. Low supply voltage.

How do you diagnose P0638?

1. Clean the throttle body and run the relearn 2. Compare commanded and actual throttle angle 3. Check the motor wiring and supply

Can I drive with P0638?

Not recommended. P0638 can lead to stalling, limp mode or engine damage; diagnose it before driving further.