Chasing an SES light...

[Muleears]

New to me '05 X5, 290K miles. I have a NT 510 that tells me I have a bad O2 sensor (alternately on each bank). I have replaced both upstream O2 sensors and I still get the bad upstream O2 code. Could this be a bad MAF? I cleaned the MAF with CRC MAF cleaner, cleared the code but it came back after about 10 miles. So as it stands now, I have a "clean" MAF and two new upstream O2 sensors, but still get the O2 sensor error code. Where do I go from here?

[Overboost]

Originally Posted by Muleears

New to me '05 X5, 290K miles. I have a NT 510 that tells me I have a bad O2 sensor (alternately on each bank). I have replaced both upstream O2 sensors and I still get the bad upstream O2 code. Could this be a bad MAF? I cleaned the MAF with CRC MAF cleaner, cleared the code but it came back after about 10 miles. So as it stands now, I have a "clean" MAF and two new upstream O2 sensors, but still get the O2 sensor error code. Where do I go from here?

Does your Foxwell give you a Pxxxx code?

[Muleears]

I have two Foxwells, a simple one that will give me the P code and a simple explaination and the NT 510 which give me more detail. However... I have foolishly deleted all the codes both from the X5 and the scanner so I don't have a record at the moment of what those codes were. I'll drive somewhere tonite or tomorrow morning and the code will come back and I'll record everything and post it here. The only code I do have, and I got this only once on the NT 510 is "8 DME: signal, air-mass flow sensor". This was what prompted the cleaning of the MAF. I will read and post here the codes as soon as I have them. Thanks again, Overboost. You must be by now with all the stuff I've posted...

[Overboost]

I would suggest monitoring maf value in grams/second with engine running at idle and NO electric devices on (lights, radio, AC, etc.) Should be around high 3's. Then on your drive look at short term fuel trims and long term fuel trims on both banks. We need to know if you are seeing a O2 too lean or too rich code. Anything over +/- 10% correction will throw your check engine light.

[Muleears]

Originally Posted by Overboost

I would suggest monitoring maf value in grams/second with engine running at idle and NO electric devices on (lights, radio, AC, etc.) Should be around high 3's. Then on your drive look at short term fuel trims and long term fuel trims on both banks. We need to know if you are seeing a O2 too lean or too rich code. Anything over +/- 10% correction will throw your check engine light.

I'm going to have to read the manual on the 510. I think it will do what you ask but I don't yet know how. I'll see if I can figure it out this evening and get some good data tomorrow. I have dinner with my son and his girlfriend tomorrow evening so I won't have all day. Then over to my daughters for Christmas day. I better get to it! Thanks for the assistance, this is my best present so far!

[andrewwynn]

You can get P codes with the NT510 If you use obd vs BMW.

I recently replaced all my O2 sensors first back then front. After replacing the front, started getting codes. First oddly post cat then front and then they would trigger every drive.

Problem was solved when I used NT510 to reset engine adaptations. I noticed instantly my long term fuel trims were zeroed then I noticed my mpg jumped 15% higher then I noticed no more ses for the next several hundred miles.

I dont know why sometimes people get away with O2 sensor swap so reset but maybe they unplugged battery doing the repair.

[Muleears]

I went for a short drive hoping to get the SES light to come back on but no luck in 5 miles. After arriving back home I thought I'd read the codes anyway. The BMW mode on the 510 found one: "EC DME: trimming, oxygen sensor before cat. bank 2". When I switched to the OBDII mode as suggested (to get the P code) there were no fault codes. The OBD II mode didn't find any. Could this just be a "pending" code and that is why it didn't show up in the OBDII but did in the BMW mode? I'll have the opportunity to drive more tomorrow and I'm sure get a P code tripped.

Btw, I did (I think) a data stream scan of the O2 sensors in operation. It recorded 5 frames of data but I have no clue what I'm looking at or for... Wish I could post it but don't know how. As usual, very appreciative of all help provided.

[andrewwynn]

That was the identical code I had.

Find the reset adaptations in the DME module.


In obd mode you you need to check each module separately

[Muleears]

Originally Posted by andrewwynn

That was the identical code I had.

Find the reset adaptations in the DME module.


In obd mode you you need to check each module separately

Will do. Thanks. I hope that fixes it!

[andrewwynn]

I'll bet a beer. I did the same thing as you got the same exact error and it hasn't come back since the reset.


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