HU9 - Check For Proper Operation of Related Engine Systems

- Verify that the following engine systems have been properly diagnosed and corrected before proceeding with the Air Intake system diagnostics:
- Positive Crankcase Ventilation (PCV) System.
- Exhaust System.
- Engine Cooling System (engine coolant temperature is above 160 degrees F).
- Incorrect fuel pressure, plugged fuel filter, fuel quality (contamination).

- Have the above systems been properly checked and are they functioning correctly?

YES -- GO to HU10. HU10 - Check For Vacuum Leaks

NO -- For PCV System: GO to Pinpoint Test Step HG1. HG1 - Stuck PCV Valve Check

For Exhaust System: GO to Pinpoint Test Step HF1. HF1 - DTC 0420 or 0430: Check For Misfire Monitor DTCs

For Engine Cooling System: GO to Cooling System.

For Fuel System: GO to Pinpoint Test Step HC. HC - Fuel Delivery System