P0505 Idle Air Control System Malfunction

P0505 points to an idle-air-control system malfunction. The module cannot control idle speed as expected, or the idle-control circuit is outside its normal behavior.

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 unless service information explicitly calls for it; many modern systems require relearn or repair, not adjustment.

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.