Questions and Answers

Mitsubishi Montero DTC P0507
Q. Hello, My Service Engine Soon light came on over 1 month ago. I took the care to two different mechanics. Both said that they would have to do a diagnostic check prior to locating the problem.

Anyway, both received the same code: P0507. However, neither one could find the source of the problem or anything that appeared to be causing the problem. So, they turned off the light and sent me on my way. I dont know what to do and Im sick of paying for diagnostics with different mechanics who say they just cant figure it out!

I believe my 2002 Mitsubishi Montero Sport ES has an automatic transmission, I believe a 3.0 liter V-6 engine and 73,840 miles. Please help with any advice if you can. Im so concerned and I will be making a 600 mile trip very soon!

Thanks,
Sylvia C.

A. DTC P0507 "Idle control system RPM higher than expected" indicates a problem in the Idle Air Control Actuator (IAC) circuit. Here is some information on DTC P0507.

Idle Air Control (IAC) Motor Circuit CIRCUIT OPERATION:

• The idle air control (IAC) motor power is supplied from the MFI relay (terminal 1).
• The PCM (terminals 14,15, 28, 29) drives the stepper motor by sequentially turning "ON" the power transistors in the PCM and providing ground to the idle air control motor (terminals 1, 3, 4, 6).

TECHNICAL DESCRIPTION:

• The amount of air taken in during idling is regulated by the opening and closing of the servo valve located in the air passage that bypasses the throttle body.
• If there is a malfunction of the IAC system, the actual engine speed will not be identical to the target engine speed.
• The PCM checks the difference between the actual engine speed and the target engine speed.

DTC SET CONDITIONS:

Check Conditions:

• Vehicle speed has reached 1.5 kph (0.93 mph) or more at least once.
• Under the closed loop idle speed control.
• Engine coolant temperature is higher than 77°C (171°F).
• Battery positive voltage is higher than 10 volts.
• Barometric pressure is higher than 76 kPa (11 psi).
• Intake air temperature is higher than -10°C (14°F).
• 60 seconds have elapsed from the start of the previous monitoring.
• Target idle air control motor position is 0 steps.

Judgment Criteria:

• Actual idle speed has continued to be higher than the target idle speed by 200 r/min (300 r/min*) or more for 12 seconds . *: Specs in parentheses are applicable if the maximum air temperature during the previous operation was more than 45°C (113°F) .

TROUBLESHOOTING HINTS (The most likely causes for this code to be set are):

• Idle air control motor failed.
• Open or shorted idle air control motor circuit, or loose connector.
• PCM failed.

There is a troubleshooting procedure for checking the circuit and pinpointing the problem, but before doing that I would recommend cleaning the throttle body first. Many times a simple cleaning will eliminate this code.

If not, then the circuit will need to be checked and what is causing the problem repaired.