Catalytic Converter efficiency?

DAVEGLASS

MEMBER
2001 BMW 525I

I am getting four error codes from my scanner:

1. Catalytic Converter efficiency, Cyl 1-3
2. Oxygen Sensor Control Limit, Cyl 1-3
3. Oxygen Sensor ADaption Limit, Cyl 1-3
4. Oxygen Sensor Adaption Limit, Cyl 4-6.

I have read several forums in which I should look at my MAF sensor or vacuum leak or possibly the gas cap. Have you heard of such a problem with multiple problems showing up at one time.

I have replaced the O2 sensors, cleaned the MAF with cleaner from Autozone and still have the same 'Service Engine' problem.

Any suggestions.

1 Reply

KASEKENNY

MECHANIC
18,907 POSTS

More than likely you have a failing converter. However, we can run through some testing to confirm this. Here are guides that will help with all this:

https://www.2carpros.com/articles/how-to-test-a-catalytic-converter

https://www.2carpros.com/articles/catalytic-converter-replacement

https://www.2carpros.com/articles/how-to-test-an-oxygen-sensor-02-sensor

More then likely this is not a MAF sensor because basically these codes are telling you that the sensors are seeing out side the limit of where they are set. That is normally a sensor issue but since you replaced the sensors, I suspect the converters have failed.

I attached the process from the manual below on how to replace these if this proves out.

Please run through this material and let us know if you have questions. Thanks