I have a small exhaust leak on the driver's side flange. I'm wondering how much that could affect the driver's side, front O2 sensor's reading.

Since the O2 is before the leak, would the readings be off? The leak is very small and is located on the edge of the flange closest to the block; if that matters any.

I'm wondering if this could be causing a part throttle hesitation...

Thomas.

 

It will cause a false lean and the PCM will add fuel to compensate and make your car run rich.

 

Exhaust leak will cause you to run rich. I never felt a hesitation while I had an exhaust leak. Maybe somebody can shed some light on that.

 

Any idea on how the false lean get's reported? Does the front O2 report lean even though the leak is after the O2?

Thomas.

 

OH, nevermind, I'm thinking your O2 is after the leak. In your case, it shouldnt make a difference.