Answer: Kristopher, as you know, lean oxygen sensor and fuel trim codes can be some of the hardest fault codes to diagnose.

When Should I Replace The O2 Sensor? The answer to this question is complex, as these sensors are not your standard maintenance items. No indicator lights on your dashboard or other means could hint ...

Diagnostics An oxygen sensor that’s going bad or has failed altogether won’t always throw a check engine light or trip a diagnostic trouble code. Sometimes if there’s an internal problem ...

I had a test done at local auto-parts store that showed a code of PO138. They told me this indicates a problem with the oxygen sensor. I replaced the oxygen sensor and the light never went out. I ...

Answer: Even though the code is for an O2 (oxygen) sensor, it is pretty obvious the problem isn’t with the sensor itself. There are three possible types of faults which can cause oxygen-sensor ...

The P0171 "System Too Lean, Bank One" fault code you experienced is only one of the many fault codes a MAF sensor can set when under- or over-reporting the amount of air flowing into the engine.