P0638 Subaru Code - Throttle Actuator Control Range/Performance
Quick Answer
The Powertrain Control Module (PCM) compares the actual Throttle Possition (TP) with the target TP when the engine is running. Common causes include Drive-by-wire control system malfunction, Throttle actuator malfunction, Throttle valve malfunction. Severity is High - diagnose this code as soon as possible. Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
- What it means
- P0638 Subaru indicates Throttle Actuator Control Range/Performance.
- Common causes
- Common causes include Drive-by-wire control system malfunction, Throttle actuator malfunction, Throttle valve malfunction.
- Severity
- High - diagnose this code as soon as possible.
- Can I drive?
- Driving is not recommended if the warning light is flashing, the engine runs poorly, or safety-related symptoms are present.
Code P0638 Subaru Description
What are the Possible Causes of the DTC P0638 Subaru?
- Drive-by-wire control system malfunction
- Throttle actuator malfunction
- Throttle valve malfunction
- PCM malfunction
How to Fix the DTC P0638 Subaru?
Review the 'Possible Causes' above and visually examine the corresponding wiring harness and connectors. Check for damaged components and inspect connector pins for signs of being broken, bent, pushed out, or corroded.
Code Tech Notes
What is the Cost to Diagnose the Code?
Labor: 1.0
To diagnose the P0638 Subaru code, it typically requires 1.0 hour of labor. Rates vary by location, vehicle, and shop. Many shops charge between $80–$150 per hour; dealerships and metro areas may be higher, independents may be lower.
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Frequently Asked Questions about P0638 Subaru Code
1. What does the OBDII code P0638 mean on a Subaru?
P0638 indicates a Throttle Actuator Control Range/Performance issue, meaning the electronic throttle system is not operating within its expected parameters.
2. What are the common symptoms of code P0638 in a Subaru?
Symptoms may include reduced engine power, poor acceleration, erratic idling, and the Check Engine Light illuminating.
3. What causes the P0638 code on a Subaru?
Common causes include a malfunctioning throttle body, wiring or connector issues, a failed throttle actuator, or problems with the Powertrain Control Module (PCM).
4. Can a dirty throttle body trigger the P0638 code on a Subaru?
Yes, carbon buildup or debris in the throttle body can restrict movement and disrupt throttle operation, potentially triggering this code.
5. How can I diagnose the P0638 code on my Subaru?
Start by inspecting the throttle body, wiring, and connectors for damage or debris. Use a scan tool to monitor throttle actuator data and check for related codes.
6. Is it safe to drive with the P0638 code on a Subaru?
Driving with this code is not recommended, as it can cause reduced engine performance and unsafe driving conditions.
7. How do you fix the P0638 code on a Subaru?
Repairs may include cleaning or replacing the throttle body, repairing wiring or connectors, or replacing the throttle actuator module.
8. Can a software issue cause the P0638 code in a Subaru?
Yes, a faulty PCM or outdated software can cause this code. Reflashing or replacing the PCM may resolve the issue.
9. How much does it cost to repair the P0638 code on a Subaru?
Repair costs vary, but throttle body replacement typically ranges from $300 to $800, depending on labor and parts.
10. Can a weak battery cause the P0638 code on a Subaru?
Yes, a weak or failing battery can lead to electrical issues that may affect the throttle actuator system and trigger this code.
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