P0506

The P0506 code indicates that the engine's idle speed is lower than what the powertrain control module (PCM) expects. The PCM has a target idle RPM — typically between 600 and 800 RPM depending on the vehicle — and when the actual idle speed consistently falls below this target despite the PCM's attempts to raise it, this code is set.

The most noticeable symptom is an engine that feels like it's struggling to stay running at idle. You may experience stalling at stop signs or traffic lights, especially when the AC is on or when you shift into Drive. The idle may feel rough and shaky, and the engine may hesitate or stumble when you take your foot off the gas pedal.

The first thing to try is cleaning the throttle body, which is one of the most common and cheapest fixes. Carbon buildup on the throttle plate and in the idle air bypass passages is the leading cause of this code. Use throttle body cleaner and a rag to remove deposits, then perform an idle relearn procedure (often done by disconnecting the battery for 15 minutes, then running the engine with no loads until it stabilizes). If cleaning doesn't resolve it, check for vacuum leaks and inspect the IAC valve or motor for proper operation.

Severity

Symptoms

• •Engine idle speed is noticeably lower than normal
• •Engine stalls when coming to a stop or at idle
• •Rough or shaky idle, especially with AC or electrical loads on
• •Engine hesitates or stumbles when shifting to Drive from Park
• •Vehicle feels like it might die at traffic lights

Likely Causes

Estimated Cost

Common Fixes

1. Clean the throttle body and idle air control passages
2. Replace the idle air control valve or motor
3. Inspect and repair vacuum leaks
4. Replace the PCV valve and hoses
5. Perform an idle relearn procedure after repairs

Shop Parts

Related Codes