Ensure engine is at ambient temperature. Connect scan tool. Using PID/DATA monitor and record function, select ECT, IAC V and RPM PIDs. Start engine.
Engine speed should decrease as engine reaches operating temperature. If idle speed decreases, go to next step. If engine speed does not decrease, check ECT sensor, IAC valve and wiring.
Allow engine to warm to operating temperature. Check for DTC P0506, P0507 and P1504. If no DTCs are present, go to next step. If any DTCs are present, diagnose and repair as necessary.
Using scan tool, select SIMULATION TEST. Change duty value of IAC valve to 100 percent. If idle speed increases, go to next step. If idle speed does not increase, check IAC valve passages and wiring.
Using scan tool PID/DATA monitor and record function, select A/C SW, ALTF, IAC V, PSP SW, RPM and RPM DES PIDs. Ensure idle speed stays in specification when accessories are operated. See IDLE SPECIFICATIONS table. If idle speed is okay, check is complete. If idle speed is not okay, check suspect component and circuit.

IDLE SPECIFICATIONS

Condition

⁽¹⁾ Idle Speed

No Load

700-800

All Accessories On ⁽²⁾

700-800

Power Steering Operating

700-800

A/C On

800-900

⁽¹⁾	In Neutral or Park.

⁽²⁾	Headlights, fan switch is in position "3" or "4", cooling fan and rear defroster are on.

When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

• You smell fuel, burning insulation, or see smoke.

• Brakes feel soft, pull hard to one side, or make grinding noises.

• The engine overheats, stalls repeatedly, or misfires under load.

• You are missing required tools, torque specs, or safe lifting equipment.

• You are not confident in the next step or safety outcome.

Safety Warning

System Check - MPV