P0638 - THROTTLE ACTUATOR CONTROL, BANK 1 - RANGE / PERFORMANCE PROBLEM

Some vehicles are equipped with cable drive systems. In this system, the throttle body is controlled by the TPS (Throttle Position Sensor), the ECM (Engine Control Module), and an electric actuator motor in the throttle body.

The ECM uses the information provided by the TPS sensor to control the actual position of the accelerator pedal. When the actual throttle position is not within range, the diagnostic code P0638 OBDII is set. This DTC code refers to bank number 1, this is the side of the engine where cylinder number 1 is located.

Most vehicles use one throttle body for all cylinders and are generally not repairable, they have to be replaced.

• The Check Engine light turns on the dashboard.
• Acceleration problems.
• At idle or low speeds the engine may lock up.

The DTC code P0638 OBD2 can be set due to:

• Polluting elements in the throttle body.
• Defective cables or connectors. There may also be loose connections.
• A malfunction of the throttle actuator engine.
• Defective Throttle Position Sensor (TSP).

To fix the problems caused by the fault code P0638 OBDII, you must do the following:

• Inspect the cables and connectors related to the throttle actuator. If there are burned or defective wires, replace them. Also, check the connectors for corrosion.
• Disconnect the throttle actuator wiring from the PCM, then check the reference voltage to a good ground and resistance throughout the wiring system. Compare the results of these readings to the manufacturer's specifications, if they are not within specification, you should change the cable.
• If all electrical values are within the given range and the code persists, the throttle actuator may be defective. Therefore, remove the throttle body and check for obvious defects.
• Change the throttle body assembly.