P0639 Throttle Actuator Control Range/Parameter B2

P0639 – OBD-II Trouble Code Technical Description

Throttle Actuator Control Range/Performance (Bank 2)

What does the fault code mean P0639?

Some modern vehicles have a drive-by-wire throttle control system that includes a sensor in the accelerator pedal, the powertrain/engine control module (PCM/ECM), and the throttle actuator motor. The PCM/ECM uses the throttle position sensor (TPS) to monitor the actual throttle position. If this position is outside the specified value, the PCM/ECM sets DTC P0638.

Note that “bank 2” refers to the side of the engine opposite cylinder number one. There is usually one throttle valve for each bank of cylinders. Code P0638 indicates a problem in this part of the system. If both P0638 and P0639 codes are detected, it may indicate wiring problems, lack of power, or problems with the PCM/ECM.

Most of these throttle valves cannot be repaired and require replacement. The throttle body is usually held open when the engine fails. If the throttle valve is completely faulty, the vehicle can only be driven at low speed.

If codes related to the throttle position sensor are found, they must be corrected before analyzing the P0639 code. This code indicates an error in the throttle actuator control system in bank 2 of the engine, which typically does not contain cylinder number one. Other control modules may also detect this fault and for them the code will be P0639.

Possible reasons

Trouble code P0639 can occur due to problems with the throttle actuator control, the actuator itself, or the throttle position sensor. Also, faulty control network (CAN) wiring, improper grounding, or problems with the grounding wires in the control modules can cause this message. A possible cause could also be a defect in the CAN bus.

Most often, code P0639 is associated with:

1. The problem is with the gas pedal position sensor.
2. Problem with the throttle position sensor.
3. Throttle motor failure.
4. Dirty throttle body.
5. Wiring problems, including connections that may be dirty or loose.
6. PCM/ECM (engine control module) malfunction.

If a P0639 code occurs, detailed diagnostics must be performed to determine the specific cause and take appropriate corrective action.

What are the symptoms of a fault code? P0639?

The following symptoms may occur with DTC P0639:

1. Problems with starting the engine.
2. Misfires, especially in neutral gear.
3. Engine stops without warning.
4. Emission of black smoke from the exhaust system when starting the car.
5. Deterioration of acceleration.
6. The Check Engine light comes on.
7. Feeling of hesitation when accelerating.

How to diagnose a fault code P0639?

Gas pedal position sensor located on the pedal itself and is usually connected through three wires: 5 V reference voltage, ground and signal. Check the wires for a secure connection and no loose spots. Also check the ground using a volt-ohmmeter and the 5V reference voltage from the PCM.

The signal voltage should vary from 0,5 V when the pedal is not pressed to 4,5 V when it is fully open. It may be necessary to check the signal at the PCM to match the sensor. A graphical multimeter or oscilloscope can help determine the smoothness of the voltage change throughout the entire range of motion.

Throttle position sensor also has three wires and requires checking connections, ground, and 5V reference voltage. Watch for voltage changes when you press the gas pedal. Check the throttle motor for resistance, which should be within factory specifications. If the resistance is not normal, the motor may not move as expected.

Throttle motor operates based on the signal from the pedal position and predefined parameters controlled by the PCM/ECM. Check the motor resistance by disconnecting the connector and using a volt-ohmmeter to ensure it is within factory specifications. Also check the wiring using the factory diagram to find the correct wires.

For the engine duty cycle, use a graphing multimeter or oscilloscope to ensure it matches the percentage set by the PCM/ECM. An advanced scan tool may be required for an accurate check.

Check throttle body for the presence of obstructions, dirt or grease that may interfere with its normal functioning.

Explore PCM/ECM using a scan tool to check that the desired input signal, the actual throttle position, and the target engine position match. If the values ​​do not match, there may be a resistance problem in the wiring.

Wiring can be checked by disconnecting the sensor and PCM/ECM connectors and using a volt-ohmmeter to check the resistance of the wires. Wiring faults can cause incorrect communication with the PCM/ECM and result in error codes.

Diagnostic errors

When diagnosing the P0639 trouble code, many mechanics often make the mistake of focusing only on the symptoms and stored codes. The most efficient way to approach this problem is to load the freeze frame data and analyze the codes in the order in which they were stored. This will allow you to more accurately identify and eliminate the cause of error P0639.

How serious is the fault code? P0639?

Trouble code P0639, while not always causing immediate problems with the vehicle's performance, should be diagnosed and repaired as soon as possible. If left unaddressed, this code can eventually lead to more serious problems such as the engine not starting or stopping abnormally. Therefore, it is recommended to carry out diagnosis and repair to prevent potential complications.

What repair will help eliminate the code? P0639?

To troubleshoot and reset the P0639 code, it is recommended that your mechanic perform the following repair steps:

1. Replace any defective or damaged cables, connectors or components associated with the throttle system.
2. If a malfunction of the throttle valve drive motor is detected, it should be replaced with a working one.
3. If necessary, replace the entire throttle body, including the throttle position sensor, as recommended by the manufacturer.
4. When replacing the throttle body, the mechanic should also consider replacing the pedal sensor, if specified.
5. Replace all faulty control modules, if any are found.
6. Connect or replace any loose, corroded or damaged electrical connectors in the system.
7. Replace any faulty wires in the CAN bus harness if they are identified as the source of the problem.

Careful diagnosis and implementation of the specified measures will help eliminate the P0639 code and return the vehicle to normal operation.

DTC Volkswagen P0639 Short Explanation

P0639 – Brand-specific information

Trouble code P0639 does not have a specific meaning for specific car brands. This code indicates problems with the gas pedal or throttle position sensor and can occur on different makes and models of vehicles. Deciphering and solving the problem depends on the specific vehicle and its control system. For accurate information and solution to the problem, it is recommended to contact the service documentation or a car repair specialist who specializes in a specific brand.