A high or hunting idle, a hiss under the hood, and codes for “running lean” — classic vacuum leak.
Unmetered air confuses everything
The engine computer meters every gram of air coming through the intake — air sneaking past a cracked hose or dried-out gasket is invisible to it, so the mixture runs lean and the idle hunts. Old-school ears and smoke machines find leaks fast; parts-swapping does not. The fix is often a $15 hose that had been baking for a decade.
Quick tips
- Lean codes (P0171/P0174) plus rough idle = suspect a leak first
- An idle that changes when you press the oil cap down is a big clue
- SoCal heat cooks rubber lines; they crack from the outside in
Need hands on the car instead of more reading? VIPCANIC comes to your driveway anywhere in the South Bay, 24 hours a day, call (310) 340-6775.
Stranded, stuck, or just done with repair shops?
One call and a VIPCANIC mechanic is on the way. 24 hours a day, anywhere in the South Bay.
Call (310) 340-6775