P0506 Idle Air Control System RPM Lower Than Expected

P0506 indicates idle speed is lower than expected. The engine is idling below the control module's target even though the module is trying to manage it.

Code status

Needs verification

Not yet verified against SAE J2012_202509 / J2012DA. Treat unverified rows as a lookup aid, not repair authority.

System
Speed / Idle
Scope
iso-sae-controlled-p0
Standard
SAE J2012 / ISO 15031-6
Source
legacy-import

Diagnostic boundary

A diagnostic trouble code reports that a monitored test failed. It does not prove one specific part is bad, and manufacturer logic can add vehicle-specific conditions.

Do not adjust mechanical throttle stops to raise idle unless service information requires it; modern systems usually need repair or relearn.

Useful checks before replacing parts

Related OBD-II codes

These nearby speed / idle entries can help compare wording and fault area. They may share the same verification status as the source database.