P0506 - Idle Control System RPM Lower Than Expected

Idle speed is lower than the ECM expects.

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

1. Inspect the related connector and harness for idle-control components
2. Inspect and clean the throttle body if carbon buildup is present
3. Compare commanded idle data to actual idle speed on the scan tool
4. Perform the idle relearn procedure if the vehicle requires it

Repair Difficulty

Moderate

General difficulty estimate for the most common repair path.

Likely Repairs & Cost Guides

Use test results to confirm the fault before pricing the repair.

Related OBD Codes

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Next Steps

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