After Cat fuel trim Error
 

I have an E53 / M54. I just changed pre and post O2 sensors for # 4 -6 bank. I did not get wires crossed. Error E2 came on. Can anybody please help? Thanks!

Pre & Post CAT O2 Sensors
 

I have an E53 / M54. I just changed pre and post O2 sensors for # 4 -6 bank. I did not get wires crossed. Error E2 came on. Can anybody please help? Thanks!

Thanks trader4 -

I have a BavAuto code reader and code E2 from table 19 says, "After CAT Fuel Trim".

What O2 sensors did you use?

Could it mean "after cat O2 sensor trim"?

Bosch

Did you have the E2 code or any other before you changed the sensors?

Could be the efficiency of the cat for that bank. The post cat 02 sensor doesn't control fuel trim like pre cat 02 sensors. One simple test to perform is if you have an infrared thermometer is to drive the car until the temp is up and use the infrared thermometer to measure the temp at the inlet of the cat and at the outlet of the cat. The outlet temp should be greater then the inlet temp if the cat is working properly.

Suspect couple of things going on - simple code reader converts and groups 4 digit codes to 2 digit. Some fidelity is lost there...

New part can be defective, someone else's return, or just plain counterfeit. Glad at least it's a name brand sensor

As pall night suggested, it could be a bigger problem that replacing O2 sensor didn't fix.

I was getting these errors on my BavAuto code reader:
E2 - After Catalytic Converter #4-6
EC - Pre Cat Fuel Trim System #4 - 6
8F - DM-TL Leak Detected
F2 - Misfire Cylinder #5

I replaced both the Pre and Post Cat O2 Sensors w/Bosch.
They are the correct ones. P/N's 15109 for Post and 13477 for Pre.

After i replaced all of the above codes went away BUT, code E2.

Any of this make more sense?

Thanks!

Depending on what type of misfire it was and how long you have been driving with the misfire, you CAT could be toast.

Did you perform the test that I suggested in my previous post.

I was getting these errors on my BavAuto code reader:
E2 - After Catalytic Converter #4-6
EC - Pre Cat Fuel Trim System #4 - 6
8F - DM-TL Leak Detected
F2 - Misfire Cylinder #5

I replaced both the Pre and Post Cat O2 Sensors w/Bosch.
They are the correct ones. P/N's 15109 for Post and 13477 for Pre.

After i replaced all of the above codes went away BUT, code E2.

Any of this make more sense?

Thanks!
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Thanks Upallnight!

Temperature post Cat is +/- 400F
Temperature pre Cat is +/- 200F
These temps are for both banks
It's difficult to measure the pre Cat Temps.
Do these temps look about right?

Any ideas?

Hello Group - Still desparately looking for some insight! Please help!!!

What was the answer to the question as to why you replaced the sensors?

Need to replace 02 sensors in pairs. Cant just do front and rear in one bank.

I'm sorry, there is no clear answer to this. A couple of thoughts - just guesses...

1) The Bav Auto code reader isn't helping much. It is somehow translating several different possible BMW codes (4 digits) into one of a few 2 digit codes. Find a friend or indy shop that can read the actual BMW codes and post those.

2) post-cat O2 sensors mostly report on the health of the cat. Very few reasons one would throw a code except the O2 sensor is bad. You could try switching the left and right side post-cat O2 sensors and see if the code follows the sensor. If it does, you got a bad sensor.

3) If you get your hands on a proper BMW code reader, clear the adaptations. It is possible the engine is still trying to read the new O2 sensor based on the map it learned from your old O2 sensor.

+1 on the logic here.

If you have an Android phone or an Android tablet, get the app Torque. Use the app features to look at the short term fuel trim and long term fuel trim in bank one and two. Yes even if you have the M54 engine, there is two banks.

This way you can determine if gas is being added to the mixture (to lean of a condition) or being taken away (too rich of a mixture). You can determine if both banks are being affected or just one bank.

:iagree: Past the time to step back and run thorough diagnostics.

The computer compares readings across the two banks. If one 02 is not working as well it can throw things off. If your replacing them because they are old (+/-100k miles) you should do the pairs. You can see in INPA how it reads against each bank.