2003 Ford Expedition PO171 PO174 P2195 P2197 - Rough Idle and Check Engine Light
Yesterday my 2003 Ford Expedition's check engine light came on. The vehicle runs roughly and erratically at idle, as if it's struggling to find the correct idle speed. It performs smoothly after warm-up and at higher speeds. I'm seeing fault codes PO171, PO174, P2195, and P2197, but I can't locate P2195 and P2197 in my owner's manual or code reference book. These codes typically indicate issues with air-fuel mixture and fuel pressure regulation, possibly due to a vacuum leak or sensor malfunction.
PO171 and PO174 are commonly linked to vacuum leaks. The most frequent location is the PCV (Positive Crankcase Ventilation) elbow where it connects to the throttle body adapter. A leak here can cause an imbalance in the air-fuel mixture, leading to rough idle and misfires.