P0511

DTC P0511 IDLE AIR CONTROL CIRCUIT

CIRCUIT DESCRIPTION

DTC Detection Conditions:

The Idle Air Control (IAC) valve, of a rotary solenoid type, is located under the throttle body. Intake air, bypassing the throttle valve, flows into the IAC valve through a passage. The valve regulates the volume of intake air that bypasses the throttle valve and allows the engine idling speed to be controlled.

The IAC valve is used by the ECM to perform idle-up and its feedback signal is used as one factor in target engine idling speed regulation.

MONITOR DESCRIPTION

Monitor Strategy:

Typical Enabling Condition:

Typical Malfunction Thresholds:

Component Operating Range:

The IAC valve controls the volume of air that bypasses the throttle valve.
Idling speed is determined by the volume of air that passes through the Intake Air Control (IAC) valve. When the volume is large, the idling speed increases. Conversely, when it is small, the idling speed decreases. the ECM sends a duty signal to the IAC valve and drives the IAC valve motor to regulate this air volume. If any of the following conditions apply, the ECM determines that the IAC system is malfunctioning, and illuminates the MIL and sets a DTC. The actual engine idling speed does not reach the target idling speed, the IAC learned valve angle remains at the maximum or minimum, or the duty ratio signal to the IAC valve is stuck.

Example:
The ECM sets DTC P0505 if either of the following conditions applies:
- The difference between the actual and target engine idling speeds exceeds 200* rpm while the engine idles, and this occurs 5 times.
- The IAC learned valve angle remains at the maximum or minimum for 5 seconds.

The ECM sets DTC P0511 (open/short circuit) if the following condition applies:
- The duty ratio signal to the IAC valve is stuck at 0% or 100%.
*: The threshold varies according to engine load.

Wiring Diagram:

INSPECTION PROCEDURE

HINT:
- When the throttle position is slightly opened (the accelerator pedal is slightly depressed) because a floor carpet is overlapped on the accelerator pedal, or if not fully releasing the accelerator pedal, etc., DTC P505 will possibly be detected.
- Read freeze frame data using a hand-held tester or OBD II scan tool. Freeze frame data record the engine condition when malfunctions are detected. When troubleshooting, freeze frame data can help determine if the vehicle was moving or stationary, if the engine was warmed up or not, if the air-fuel ratio was lean or rich, and other data, from the time the malfunction occurred.

Step 1 - 3:

Step 4 - 7:

Step 8 - 9:

Hand-held tester

Step 1 - 5:

Step 6 - 8:

OBD II scan tool (excluding the hand-held tester)

CHECK FOR INTERMITTENT PROBLEMS

HINT: Hand-held tester only:
Inspect the vehicle's ECM using check mode. Intermittent problems are easier to detect with a hand-held tester when the ECM is in check mode. In check mode, the ECM uses 1 trip detection logic, which is more sensitive to malfunctions than normal mode (default), which uses 2 trip detection logic.

a. Clear DTC.
b. Switch the ECM from normal mode to check mode using a hand-held tester.
c. Perform a simulation test.
d. Check and wiggle the harness(es), connector(s) and terminal(s).