1999 E430 Check Engine Light
 

Recently my check engine light came on after I noticed that fuel tank wasnt filling up all the way. The tank will only allow me to fill up 3/4 of the tank. I've just taken it into an Autozone to get the codes check out and it came out: Explantion:" The powertrain control module uses the oxygen senor to calculate the air/fuel ratio of the engine. The computer has recongized a rich or lean condition on one engine bank only." I had no clue what that meant. If you have any information on this please respond.

Thank your for taking the time to Read.

According to the parts department (Fastlane, above), your car comes with two oxygen sensors. I would guess that one of them is no longer working correctly.

I would guess the O 2 sensors are working fine and they told the engine management system the car was rich or lean. The engine management system then used software to compensate but eventually it ran out of capability to compensate for the problem. The real problem is that you have only seen the tip of the iceberg in diagnostic data. You don't even know rich or lean. What you now need to know is which adaptive limit was reached and which way it was compensating.

The answer lies in the current adaptation numbers. Go tell AZ that you want adaptation numbers in enhanced data, not generic BS.