P0639Generic code

P0639 Code: Throttle Actuator Control Range/Performance (Bank 2)

The P0639 code means the second electronic throttle, on engines that have two, is not following the position the computer asks for. Like P0638, it is usually caused by carbon buildup or wear.

Severity
High
Can I keep driving?
Yes, but with caution
Estimated cost
$0 to $800
Difficulty
Medium
System
Air and Fuel
Applies to
All OBD2 vehicles

Updated Reviewed by Renzo Chacca

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What the P0639 code means

Some V8 and V12 engines have one throttle body per bank. The P0639 code refers to the one on bank 2.

The diagnosis is the same as for P0638: compare the commanded position with the real one, clean the throttle body and run the relearn.

As on bank 1, carbon builds up around the throttle plate and slows it down when it closes. Clean the throttle body with the key off, and do not force the plate open with your fingers, because the motor and gears are delicate. Then relearn both throttle plates. On engines with two throttle bodies, the computer needs them to be synchronized.

P0639 code symptoms

  • Limp mode.
  • Unstable idle.

Likely causes of the P0639 code

  1. Carbon that makes the throttle plate stick.
  2. Worn throttle body motor.
  3. Loose or corroded connector.

How to diagnose the P0639 code step by step

  1. Compare the desired and actual position on the scan tool.
  2. Clean the throttle body and run the relearn.
  3. Relearn both throttle plates so they end up synchronized.

How to fix the P0639 code

  • Clean or replace the throttle body.

Technical reference data

  • Two throttle bodies on some V8 and V12 engines.
  • Reference values: check the manufacturer data for your vehicle.

Brand-specific notes

This code appears on engines that use one throttle body per bank, so it is mostly seen on large engines.

P0639 on BMW V8 and V12

It appears on BMW V8 and V12 engines.

P0639 on Mercedes V12

It appears on Mercedes V12 engines.

Frequently asked questions about P0639

Can I drive with a P0639 code?
With caution. The vehicle can drop into limp mode with very little power, so avoid busy roads until it is repaired.
What is usually behind it?
Carbon buildup around the throttle plate. A worn throttle body motor is the next most likely cause.
Do I have to run a relearn?
Yes. Relearn both throttle plates after cleaning or replacing the throttle body, so the computer keeps them synchronized.
How much does it cost to fix P0639?
Between $0 and $800. A cleaning you do yourself is nearly free, and a new throttle body on a V8 or V12 is at the top of the range.
What does the P0639 code mean?
It is a generic OBD2 code that means the bank 2 throttle actuator is not reaching the position the computer asks for.
What is the most common cause of P0639?
Carbon around the throttle plate. When a P0639 code shows up on an engine with two throttle bodies, cleaning is the first thing to try.

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