Troubleshooting
DTC P0511 Idle Air control CircuitCIRCUIT DESCRIPTION
DTC Detecting Condition:
The rotary solenoid type IAC valve is located in front of the intake air chamber and intake air bypassing the throttle valve is directed to the IAC valve through a passage.
In this way the intake air volume bypassing the throttle valve is regulated, controlling the engine speed.
The ECM operates only the IAC valve to perform idle-up and provide feedback for the target idling speed.
MONITOR DESCRIPTION
Monitor Description:
Monitor Strategy:
Typical Enabling Conditions:
Typical Malfunction Thresholds:
The idle speeds are determined depending on the volume of air that passes through the IAC valve. When the volume is large, the idle speed becomes higher. When the volume is small, the idle speed becomes lower.
The IAC valve controls the air volume that bypasses the throttle valve. The engine control module (ECM) sends duty signals to the IAC valve and drives the IAC valve to determine the air volume that bypasses the throttle valve.
Although the ECM regulates the idle engine RPM with the feedback control in several vehicle stopped, actual idle RPM dose not reach the targeted RPM and a learned valve of the idle air control (IAC) remains at the maximum or remains at the minimum, the ECM determines to detect malfunction in the IAC system.
Example:
If the RPM difference between the targeted and actual idle engine RPMs exceeds 200 rpm (*1) with the vehicle stopped in an idle, and this occurs 5 times, or if the learned value angle of the IAC remains at its maximum or minimum angle for 5 seconds, P0505 is detected.
P0511 is detected as an open/short circuit in the IAC if the rate of duty signal input to the IAC valve has stuck at 0 % or 100 %.
*1: Threshold rpm is varied by an engine load.
Wiring Diagram:
Step 1 - 2:
Step 3 - 5:
Step 6 - 7:
INSPECTION PROCEDURE
HINT: Read freeze frame data using OBD II scan tool or hand-held tester. Because freeze frame records the engine conditions when the malfunction is detected. When troubleshooting, it is useful for determining whether the vehicle was running or stopped, the engine was warmed up or not, the air-fuel ratio was lean or rich, etc. at the time of the malfunction.