Shadow22

I have a 06 bmw 530i n52 138k miles with a few code they are
2c2b lamba probe system check in front of cat.
2c31 lamba probe trim control

Iv replaced the primary precat 02 sensor and I'm thinking the rear 02 sensor is in need of replacement is it common for them to go out at the same time? Car has 138k miles I replaced the prcat about 1000 miles ago when I replaced the disa valve that failed and was found in my intake port. Car Was fine for a while then these came up. Any help is appreciated. Thank you

seanjordan20

Have you done a heat test on it? I would never replace just on. Its always best practice to replace both because if one goes the other is not far behind depending on how long you drove on the bad one. I would first test and make sure that is your problem. A laser thermo is cheap and can assist with testing.

There is no definitive answer on when an O2 sensor goes they could last 100k or 250k. If one goes then always replace the other.

Shadow22

Do you want me to test the temperature before the converter and after to converter to see if the cats clogged? Or test the temperature where?. And can you verify that the downstream 02 sensor is only to test cat efficiency or dose it control fuel trim also? Thanks for the help.

seanjordan20

you test before and after. This will tell you either your O2 sensor is bad or converter. The converter should not be bad though. If you are seeing it red hot (by temp or visual) after a drive then it is clogged. Did you replace the O2 sensor with OEM? Are you running a flash?

If you see the difference in temp one warmer than the other then you are good stream wise and should test the injectors/coils. Also an exhaust leak can give you those codes.

Shadow22

do you know what the temps should be close to? i also have a camera i can use to look down the pipe down the 02 bung and see the converter.
i replaced bank 1 sensor 1 with a bosch exact fit sensor. my understanding is there are 4 different 02 sensors for the car and each pre cat and post cat sensor is a different bosch part number. everything on the car is stock except the k&n filter but in original box. im thinking i have a good sensor but just bad wiring because when i changed the oil pan gasket i dropped the sub frame and im pretty sure i may have pulled some wires loose but im just unclear of how to find the short at the computer end because all my scan tool reads is the precat sensors in miliamps and not volts i understand that they are wide band sensors and 6 wire so they are out of my league unlike the older 4 band sensors. even the post cat sensors stay at around .6 to .7 volts. but the front 2 both read around .2 miliamps.
and the short term and long term fuel trims are all within -2 to 7%..
dose anyone know how to test the precat wideband 02 sensor of the car or on the car? im in the process of downloading INPA software to look deeper into the problem. but as soon as i clear the codes on bmw carley on my phone they come back after 2 restarts the codes 2c31 and 2c6b. frustrating since my inspection goes out in march. i also bought all 6 coils about 6000 miles as matinence because am the second owner. they were also bosch coils. i dont have any misfires.

Boy Fernando

i'm trying to replace the oxygen sensors on my 2004 530i, and i got stuck. I can't remove that thing (plastic thing that cover/holds some electrical wire) that blocks one of the nuts that hold down the right engine cover. the way i look at it, i think it is attached to the stress bar. Any ideas how can i remove that thing?