P0638
Throttle Actuator Control Range/Performance Bank 1
Throttle actuator control
Generic OBD-II
High
What it means
P0638 means the throttle actuator control for bank 1 isn't achieving the throttle position the ECM commanded. Because this is the electronic throttle, the car often drops into reduced-power 'limp' mode and may hesitate or stall. It's commonly the throttle body itself or its wiring, and should be addressed promptly.
High
Can I keep driving? Limited — the car often drops into reduced-power 'limp' mode and may hesitate or stall, so drive cautiously and address it promptly.
Common symptoms
What you'll notice
- Reduced engine power or acceleration (limp mode)
- Check-engine light on
- Poor or sluggish throttle response
- Hesitation or stalling during acceleration
Common causes
Most likely first
- Faulty throttle body / throttle actuator motorLikely
- Dirty or sticking throttle plateCommon
- Damaged wiring or connectors in the throttle actuator circuitCommon
- Loose or corroded electrical connectionsLess often
- Faulty engine control module (ECM)Less often
How to diagnose & fix
Work through it in order
- Inspect the throttle body connector and wiring for damage, corrosion, or loose pins.
- Clean the throttle body if the plate is carbon-fouled or sticking.
- Test the throttle actuator motor and position feedback; replace the throttle body if it can't reach commanded position.
- Perform a throttle relearn after any repair; if the fault stays, suspect the ECM. Clear and re-test.
FAQ
Quick answers
Is it safe to drive with P0638?+
Only cautiously. The electronic throttle may limit power or cause hesitation or stalling, which is risky in traffic. Get it fixed promptly.
Can I just clear P0638?+
It usually comes right back and drops into limp mode again until the throttle body or wiring is repaired. A throttle relearn is often needed after the fix.
Related codes
Often seen with P0638
Read & clear P0638 yourself
Scan your car, confirm the code, and clear it once it's fixed — with OBD DashX on your phone.
✓ Verified name — SAE J2012 / ISO 15031-6Guidance reviewed by OBD DashX