DIY: Oxygen O2 Sensor Change Fixed Rough Idle and Limp Mode

[pyhee]

Hi All,
In short: A bad oxygen sensor before catalyzer on bank 1 has caused me rough idle, misfiring codes and deteriorated the situation into limp mode. I replaced the O2 sensors before cat on both banks, reset adaptation and completely solved the problem.

I have made the DIY work a YouTube video, hoping this will help you guys who have the same issue. Please watch:

***Parts Required***
Oxygen sensorBEFORE CATALYZER X2
BMW 11 78 7 537 984
Bosch LS 17038 / 0 258 017 038

***Tools Required***
8 mm hex socket (trims)
10 mm hex socket (trims)
17 mm hex socket (reinforcement strut/plate bolts)
torque wrench with angle (56 Nm)
22 mm open hex spanner (O2 sensor)
22 mm open hex torque spanner (25-50Nm)

***Work outline***
1. Remove transmission cover
2. Partially release bumper lower trim
3. Remove reinforcement strut/plate
4. Replace O2 sensors before cat
5. Reset adaptation
6. Test run
7. Assembly

***My Symptoms in order of occurrence***

1. Codes about O2 sensor before catalyzer on bank 1
   The car did not have serious sickness at this moment. The code could be cleared and would come back some time after driving. It would not come back right at next start.
   
   Below are the history random codes (they come randomly);
   2724 DME: Oxygen sensor, signal before cat., bank 1
   2726 DME: Oxygen sensor, plausibility before cat., bank 1
   2728 DME: Oxygen sensor, coast-mode diagnosis before cat., bank 1
   2742 DME: Oxygen sensor heater resistance diagnosis before cat. converter, bank 1
   2748 DME: Oxygen sensor before cat., evaluation module in control module, bank 1
   277C DME: Oxygen sensor trim control diagnosis, bank 1
   
   I ignored it because I though it was caused by my exhaust mod. Shame on me.
2. Loss of power at drive-off
   After start, the car seemed didn't want to leave the parking space. Pressing more on the throttle peddle didn't help. But shortly normal driving was possible.
3. Rough idle
   The kicking and knocking of engine became noticeable. And it always occur at idle, no matter the engine was cold or hot. It became an earthquake as days went.
4. Limp mode
   The shaking at idle became so serious that misfiring was all over cyl 1-4 and ONLY on bank 1. There were misfirings with fuel cutoff. The car went into limp mode.
   
   Below are the codes accompanied with limp mode;
   2B35 DME: Misfire with cutoff, cyl. 1
   2B36 DME: Misfire with cutoff, cyl. 2
   2B37 DME: Misfire with cutoff, cyl. 3
   2B38 DME: Misfire with cutoff, cyl. 4
   2B41 DME: Misfire with cutout, several cylinders
   2B42 DME: Misfire impairing exhaust emission, cyl. 1
   2B43 DME: Misfire impairing exhaust emission, cyl. 2
   2B44 DME: Misfire impairing exhaust emission, cyl. 3
   2B45 DME: Misfire impairing exhaust emission, cyl. 4
   2B4E DME: Misfire impairing exhaust emission, several cylinders
   
   Restarting could exit the limp mode but the rough idle will trap the engine again.

[DrFerry]

Great DIY and thorough video. Thanks for making and posting. Isn't the Bosch O2 sensor 'before' the catalyst = 17039 and not 17038?
https://www.fcpeuro.com/products/bmw...nt-bosch-17039
.
OR did the BOSCH part number recently change?
.

[Ximian]

Originally Posted by DrFerry

Great DIY and thorough video. Thanks for making and posting. Isn't the Bosch O2 sensor 'before' the catalyst = 17039 and not 17038?
https://www.fcpeuro.com/products/bmw...nt-bosch-17039
.
OR did the part number change?
.

That has to be a typo on the name. If you scroll down, you can see the full part numbers. Verify by the OE number, which is for a pre-cat O2 sensor.

OE Numbers
11787537984

MFG Numbers
17039, 0258017038

[DrFerry]

Originally Posted by Ximian

That has to be a typo on the name. If you scroll down, you can see the full part numbers. Verify by the OE number, which is for a pre-cat O2 sensor.
OE Numbers
11787537984
MFG Numbers
17039, 0258017038

I could buy that explanation (which is a good one) if it wasn't for the fact that in his DIY video above he shows an image of the box and its part number. I posted that same image above and here below which shows 17038 ? and not 17039. I agree the OEM Part number for the primary before Cats lambda probe is = 11787537984 and that equates to Bosch sensor = 17039... which is different to what is shown in the video and image below. It's not a big deal since we know how to identify the correct part, but I thought the discrepancy was worth pointing out for others on a DIY thread. The OP even has 17038 stated in his original post above..

https://www.realoem.com/bmw/enUS/par...&q=11787537984
.
https://www.fcpeuro.com/products/bmw...nt-bosch-17039
.

[Ximian]

16421 and 16793 are the Bosche part numbers for the post-cat sensors. Looking at it further, it appears 17038 is either an older revision of 17039 or just meant for a different area, so still correct information there.

[cloumeM]

17039 Bosch worked for me. Thanks OP.