LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Lexus >> 2004 >> SC 430 >> Repair and Diagnosis >> Engine Performance >> System >> SFI System - Diagnosis >> DTC P0505: Idle Air Control System >> Monitor Description
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Monitor Description

The ECM regulates the idle speed by opening and closing the throttle valve using the ETCS. The ECM concludes that the idle speed control ECM function is malfunctioning if: 1) the actual idle RPM varies more than the specified amount five times or more during a drive cycle; or 2) a learned value of the idle speed control remains at the maximum or minimum five times or more during a drive cycle. The ECM will turn on the Malfunction Indicator Light (MIL) and set a DTC.

Example:

If the actual idle RPM varies from the target idle RPM by more than 200 rpm (varies with engine load) five times during a drive cycle, the ECM will turn on the MIL and set a DTC.

Fig 1: Monitor Description
G01447847Courtesy of © TOYOTA, LICENSE AGREEMENT TMS1002