Dtc P0171 Code
Racer
Joined: Jul 2006
Posts: 285
Likes: 1
From: Placentia CA
P0171 : System lean bank 1. On our cars that's the left side, Cyls. 1-3-5-7. The PCM is not seeing what it expects to see from the left front Oxygen sensor (B1S1). Look for a vacuum leak that affects just that side of the engine. I suppose an exhaust leak could do it too as air could be pulled in, more likely with headers that with cast manifolds. If you can’t find any leaks it’s time to look at the sensor output. You will have to decide if bank 1 really is lean or is the sensor starting to go flat. Anyway hope this points you in the right direction. Good luck
