What is the P0638 fault number? What is the Throttle Actuator Control Zone / Performance (Bank 1) fault? How do I fix the P0638 fault code What are the symptoms and causes for the P0638 fault code
What is the P0638 Fault code? What does it signify?
P0638 is a general fault codes that can be used to identify problems. “Throttle Actuator Performance/Control Range (Bank 1)” . This code is set when the powertrain control module, PCM, detects an issue with the throttle control actuator operation in electronically wired systems. The “range/performance” The code defines issue as a condition where the throttle control actuator does not operate as expected. “Bank 1” Refers to the engine row that contains cylinder 1 in engines that have two engine rows (V6/V8). However, most vehicles only use one throttle for all cylinders. Some applications may require that the fault occur for 8 driving cycles in order for the PCM register a fault code.
Electronically controlled wired systems do not have a physical connection between the accelerator pedal, and the throttle. These applications use an electric motor that is controlled by the PCM. This control module uses input data from several control modules to control the throttle. Some modules are:
- – Transmission control Module
- – Body control module
- – ABS control module
- – Fuel control module
- – Turbo control module
- – Cruise control module
- – Traction control module
- – Stability control module
- Distance warning module
Other control modules may exist, but the throttle control process begins when the accelerator pedal presses. The position sensor within the accelerator pedal assembly transmits the pedal position as well as the pedal speed via the CAN bus to both the PCM (and all other modules affected) listed above. This information is also shared with the PCM from all modules involved in safe vehicle operation. This ensures that the PCM is able to verify that all control module receive throttle input data. The vehicle will then start accelerating. The whole validation and checking procedure takes less than one second. Once everything is checked, the PCM orders the throttle motor to adjust the throttle plate to a desired position. A position sensor (TPS), which is located within the throttle, reports the PCM the current position on the throttle plate. Fault code P0638 will be set if the throttle position is not in line with the requested position by the PCM.
Some situations can occur depending on your vehicle’s specifications when the throttle request is sent. If your vehicle has an automatic transmission, for example, the PCM will issue gearshift commands to respond to the throttle request. If your vehicle has adaptive cruise control, and you are too close to it, the distance control module might prevent the throttle from responding. To avoid potential hazards, the brakes can automatically engage.
The P0638 fault code can affect vehicles of all makes and models, including but not limited to Mini, Mitsubishi, Renault. Subaru, Hyundai. Skoda. Audi. Saab. Isuzu. BMW. Volvo. Volkswagen. Suzuki. Opel. Fiat. Mazda. It is not.
What is the P0638 Fault Code and Why Does It Happen?
Below are some reasons to set fault code P0638:
- – Defective accelerator pedal position sensor
- – Defective throttle position sensor
- – Defective throttle actuator
- – Dirty throttle bodies
- – Defective brake pedal (also known as brake switch)
- – Short-circuited cables and connectors that are damaged, melted or corroded.
- – Damaged cables/components on the controller network bus
- – Other fault codes can be set
- – Incorrectly or defectively programmed PCM
What are the symptoms for P0638 Fault Codes?
You may experience the following symptoms if your vehicle has the code P0638:
- – Illumination for the check engine light
- – When you press the accelerator pedal, the vehicle might hesitate/stumble.
- – Even if you don’t press the accelerator pedal, the vehicle can accelerate on its own.
- – Difficulty or no starting the vehicle. These symptoms can vary depending on whether the vehicle’s temperature is high or low.
- – Engines may stall often or unexpectedly when the engine is idle or at low engine speeds
- – The maximum allowable RPM may be exceeded or fluctuated by the idle speed
- – Setup of any other relevant fault codes (eg, cylinder misfire codes).
How to Fix the P0638 Fault Code
You cannot fix the P0638 fault code if your vehicle has this throttle body. Sometimes the only thing you can do is replace the throttle body.
The following repairs may be able to resolve the P0638 fault code:
- – Repair or replace damaged, disconnected, corroded and shorted connectors, parts, wiring, and components associated with throttle actuator
- – Cleanse the throttle body
- – Replacing a defective throttle actuator
- – Replacing the defective PCM
Note: If the fault codes for the brake pedal switch are linked together with this code then the brake pedal switch cable and sockets must be checked first.
How Serious Is the P0638 Fault Coding?
P0638 means that there is a very serious fault. The vehicle may not start until the problem is fixed. Even worse, the vehicle might not respond to your accelerator pedal, which can put you in danger. This code should be fixed immediately.
