Fix code P0171 on Ford Focus
Fords are notorious for P0171 vacuum leaks. This model is now different. It’s hard to find a P0171 leak on these newer cars because of the plastic intake manifolds. The whooshing sound is conducted by the plastic manifold, making it harder to listen for a leak. However, the most common failure on these vehicles is the positive crankcase ventilation (PCV) hose or the PCV elbow. That should be the first thing you check/replace.
© 2012 Rick Muscoplat