Throttle Closed Position Performance (GM)
What does P1524 mean?
The P1524 code means the vehicle's onboard diagnostic system has detected: Throttle Closed Position Performance (GM). This is a moderate severity code.
Common Symptoms
- High idle speed
- Check Engine Light illuminated
- Reduced engine power warning possible
- Engine does not idle down when foot is off the gas
- Stabilitrak or traction control warnings
Probable Causes (Ranked by Likelihood)
- Carbon buildup preventing full throttle plate closure Very High
- Faulty throttle position sensor at closed position High
- Throttle body motor not returning plate to closed Moderate
- Damaged throttle body spring Moderate
- ECM calibration error after battery disconnect Low
Step-by-Step Diagnostic Procedure
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Check TPS voltage with the throttle in the resting (closed) position. It should be approximately 0.4 to 0.6V.
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Clean the throttle body bore and plate edges thoroughly.
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Perform a throttle body relearn with a scan tool or key-on procedure.
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Inspect the throttle body for a damaged return spring.
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If the throttle plate does not close fully, check for physical obstruction or a worn motor.
Frequently Asked Questions
What is throttle closed position performance?
The ECM monitors the TPS reading when the throttle should be fully closed. If the reading is higher than expected, it means the plate is not closing completely, which can cause high idle and other issues.
Will a throttle body relearn fix this?
If the underlying mechanical issue (carbon, wear) is not present, yes. The relearn teaches the ECM the new closed-throttle position. But if carbon prevents closure, clean first then relearn.
Can disconnecting the battery cause this code?
Yes. Disconnecting the battery clears the learned throttle position. The ECM may set this code until a proper relearn is performed. This is the most benign cause of P1524.