Bumbobee

Hey guys,

I had a lean bank 1 and 2 code and my mechanic said it was the oxygen sensors (air/fuel ratio sensor). I replaced all 3, 2 upper air/fuel ratio sensors, and 1 downstream oxygen sensor with denso sensors from rock auto.

A different code showed up now, and I still have the check engine light.

My mechanic said it was the knock sensor, but just wanted to see what these codes mean?

hzt30

P0171 - Lean on bank one
P0174 - Lean on bank two
P0325 - Knock sensor

You are getting a lean condition on both banks. Did your mechanic hook up a scan tool to determine that you needed A/F sensors? The downstream O2 sensor is to monitor the catalytic converter.

The knock sensor could be bad and there are tests for this.

PuReChaos

You could technically be running so lean, your causing pre-ignition/detonation. Should ask your mechanic to hook up a scan tool and tell you exactly what your fuel trim numbers are. Because your AF/O2 sensors could have been acting normally and it could very well have been another issue causing your system to run lean.

dodger1989

What Brand of oxygen sensors did you install. If you have installed aftermarket sensors, the first place I would start would be replacing them with factory sensors, I have had this issue many times with aftermarket sensors. That connection you see that is missing is an A/C line and has no effect on your issue. Hope this helps.