P0638 on 2001-2004 Volvo XC70 — Throttle Actuator Control Range/Performance Bank 1
1 vehicles · 1 makes · $200-$600 repair
Most Reported On
P0638 is an OBD-II diagnostic trouble code meaning “Throttle Actuator Control Range/Performance Bank 1.” This code means the engine computer detected that the electronic throttle plate (Bank 1) is not opening or closing to the position it commanded. The PCM monitors throttle actuator position against the desired angle and sets this code when they disagree. This can trigger reduced-power 'limp' mode, hesitation, or unexpected changes in engine response, which makes it a safety-relevant fault. This code is most commonly reported on 2001-2004 Volvo XC70, with repair costs ranging from $200 to $600.
Common Causes
Typical Repair Cost
Based on 1 documented vehicle-specific issues. Actual cost depends on root cause and vehicle.
Diagnostic Tools
To diagnose P0638, you'll need an OBD-II scanner. Here are our recommendations at every price point.
ANCEL AD310 Classic OBD-II Scanner
by ANCEL
A simple, affordable code reader that reads and clears check engine codes. Great for quick diagnostics on any OBD-II vehicle (1996+).
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BlueDriver Pro Bluetooth Scanner
by BlueDriver
Bluetooth OBD-II scanner with a free companion app. Provides enhanced diagnostics, smog readiness, and repair reports sourced from a database of verified fixes.
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LAUNCH CRP123X OBD-II Scanner
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A professional-grade handheld scanner that reads all four major systems (engine, transmission, ABS, SRS) with live data streaming and graphing.
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Autel MaxiCOM MK808S Diagnostic Tool
by Autel
Shop-level diagnostic tablet with bi-directional control, active tests, and full system coverage. Ideal for serious DIYers and small shops.
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- Oil reset, EPB, BMS, TPMS, injector coding
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FAQ
What does P0638 mean?
P0638 stands for "Throttle Actuator Control Range/Performance Bank 1." This code means the engine computer detected that the electronic throttle plate (Bank 1) is not opening or closing to the position it commanded. The PCM monitors throttle actuator position against the desired angle and sets this code when they disagree. This can trigger reduced-power 'limp' mode, hesitation, or unexpected changes in engine response, which makes it a safety-relevant fault.
What are the most common causes of P0638?
The most common causes of P0638 are: Dirty or carbon-clogged throttle body, Faulty throttle actuator motor, Failed throttle position sensor, Corroded or loose throttle body connector, Wiring faults in the throttle control circuit, Mechanical binding of the throttle plate, PCM fault. The specific cause varies by vehicle.
How much does it cost to fix P0638?
Repair costs for P0638 range from $200 to $600, depending on the vehicle and root cause.
Which vehicles are affected by P0638?
Au7o has documented P0638 across 1 vehicle models from 1 manufacturers: Volvo.
Content compiled with AI assistance using NHTSA complaints, TSBs, and owner reports. May contain errors. Always verify with your vehicle's service manual.