Questions and Answers

Ford E350 Van DTC 412 Q. Mr. Ciulla, can you please provide me with information that will help me narrow down and repair OBD code 412 on my 1995 Ford E350 15 passenger van. It has a 7.5 liter engine, automatic transmission and 384,527 miles.

A. DTC 412 "Cannot control RPM during KOER self-test high RPM check." DTC 412 indicates that during the Engine Running Self-Test, engine rpm could not be controlled within the Self-Test upper limit band.

Possible causes:

• Open or shorted circuit.
• Throttle linkage binding.
• Improper idle airflow set.
• Idle Air Control (IAC) solenoid contamination.
• Items external to Idle Air Control system that could affect engine rpm.
• Damaged IAC solenoid.
• Damaged Powertrain Control Module (PCM).

Turn the key "OFF", connect a tachometer. Then start the engine and disconnect the Idle Air Control (IAC) harness connector. Does the rpm drop or engine stall?

If it does, turn the key "OFF" and disconnect the IAC. With an Digital Volt/Ohm Meter (DVOM) check the resistance of the IAC solenoid. It should be between 6.0 and 13.0 ohms. Due to diode in the solenoid, place the DVOM (+) lead on the VPWR pin and the (-) lead on the IAC pin.

If it is not within specification, replace the IAC solenoid.