P0506 - Idle Control System RPM Lower Than Expected
Idle speed is lower than the ECM expects.
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Check intake boots, PCV hoses, and post-MAF leak paths.
Inspect MAF contamination and airflow data after intake leaks are considered.
Look for cracked ducts, loose clamps, and unmetered air after the MAF.
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Code Overview
Idle speed is lower than the ECM expects.
Common Causes
- Dirty throttle body reducing airflow at idle
- Idle air control or throttle actuator not opening enough
- Vacuum leak compensation problem or incorrect relearn
- Electrical fault in the idle-control circuit
Symptoms
- Idle speed drops too low at stops
- Engine may stumble or stall at idle
- Low idle with vibration or roughness
Diagnostic Steps
- Inspect the related connector and harness for idle-control components
- Inspect and clean the throttle body if carbon buildup is present
- Compare commanded idle data to actual idle speed on the scan tool
- Perform the idle relearn procedure if the vehicle requires it
Repair Difficulty
Moderate
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Next Steps
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