E46 M3 Bosch Oxygen Sensor guide

[SkunkWorks]

There is a cutout in the plastic beauty cover for rubber block.

D'oh! Of course. Thanks you two. The beauty cover has been off the motor for so long I forgot that was even a thing...

I found the insulator hanging on the wire right beside the post-cat O2 sensor so had wrongly assumed it went under the car somewhere 😅

[Tbonem3]

Passenger side back towards the CPS. It acts as insulation for the beauty covers hole where the o2 wires and egt go. If I'm thinking of what you're describing.

[Slideways]

This might be a dumb question but in the process of installing the M3 exhaust on the wagon and I can't figure out where the square rubber wire holder with the 2 rectangular cutouts for the post-cat O2 sensors goes. Anyone know?

There is a cutout in the plastic beauty cover for rubber block.

[SkunkWorks]

This might be a dumb question but in the process of installing the M3 exhaust on the wagon and I can't figure out where the square rubber wire holder with the 2 rectangular cutouts for the post-cat O2 sensors goes. Anyone know?

[Riley]

This is exactly what I did. I have only driven it a little since installation, but so far no problems at all. It seems clear that the only differences between the four sensors really are just the connectors and wire lengths.

That is exactly the difference between all the sensors. They are all identical narrowband sensors with just different wire lengths and keyed connectors.

[D-O]

I also have supersprint headers and this is exactly what I did. Bank 2, S1 needs a longer cable. Both pre cat sensors are identical the only difference being wire length.

The part number for the bank 2 s1 connector is BMW-12521703571
Purchase a BOS-13949 (bank 1, s1) o2 sensor depin it and plug it into the new connector matching the same pin out.

This is exactly what I did. I have only driven it a little since installation, but so far no problems at all. It seems clear that the only differences between the four sensors really are just the connectors and wire lengths.

[Riley]

Front bung on both banks. On bank two the sensor can be made to work, but it is too short to route through the wire clamps in the top of the valve cover. Bank one just fits, but while trial fitting things today I discovered that bank one actually fits better using the rear bung as in orients the sensor vertically. The only concern is that this bung is much taller than the front bung and I wonder if the sensor will be deep enough in the exhaust stream.

I also discovered that the bank one sensor, which is longer than bank two, is the perfect length for bank two. I am going to use two bank one sensors and swap the connector on one of them. I will report the results.

D-O

I also have supersprint headers and this is exactly what I did. Bank 2, S1 needs a longer cable. Both pre cat sensors are identical the only difference being wire length.

The part number for the bank 2 s1 connector is BMW-12521703571
Purchase a BOS-13949 (bank 1, s1) o2 sensor depin it and plug it into the new connector matching the same pin out.

[mikeetastic]

is there a test in inpa or any bmw specific reader to show 02 sensors are working properly?

[D-O]

If I did not already have sensors, I would be tempted to try these: https://www.amazon.com/Bosch-15738-O...000BZL08U?th=1

Bosch website claims they will work in any of the four locations on our cars.

[D-O]

I am unable to confirm, but my experience with NGK sensors was that the harness and connector really drove part number variation, so they may all be the same on the sensor side.

But I'm curious, on your SS headers, are you using the bung closest to the engine? Stock sensors should reach if so; it's tight, but possible.

Front bung on both banks. On bank two the sensor can be made to work, but it is too short to route through the wire clamps in the top of the valve cover. Bank one just fits, but while trial fitting things today I discovered that bank one actually fits better using the rear bung as in orients the sensor vertically. The only concern is that this bung is much taller than the front bung and I wonder if the sensor will be deep enough in the exhaust stream.

I also discovered that the bank one sensor, which is longer than bank two, is the perfect length for bank two. I am going to use two bank one sensors and swap the connector on one of them. I will report the results.

D-O

[PSUEng]

Old thread, but I am bringing it back.

Can anyone confirm that all four sensors are the same, and that the only difference is the wire lengths and connectors? All four of mine are marked LSH25. I would like to use a new post cat sensor up front (pre cat) because one of my pre cat sensors is a bit short for the Super Sprints.

Thanks in advance.

D-O

I am unable to confirm, but my experience with NGK sensors was that the harness and connector really drove part number variation, so they may all be the same on the sensor side.

But I'm curious, on your SS headers, are you using the bung closest to the engine? Stock sensors should reach if so; it's tight, but possible.

[Obioban]

Don’t know about the sensors themselves, but the plugs are keyed.

[D-O]

Old thread, but I am bringing it back.

Can anyone confirm that all four sensors are the same, and that the only difference is the wire lengths and connectors? All four of mine are marked LSH25. I would like to use a new post cat sensor up front (pre cat) because one of my pre cat sensors is a bit short for the Super Sprints.

Thanks in advance.

D-O

[gixxer]

I pulled the Bosch P/Ns from their website and ordered from Autozone with an extra 20% off--best prices I found at the time. Running them now, and they work perfectly fine.

Did the same with Autozone with their 20% off, free delivery,

I could have saved a buck or two with RockAuto but their return policy is only 30 days compared to AutoZone's 90 days. And with AutoZone i can return to the local stores.

Quick shipment by AutoZone.

[sapote]

The sort of rule of thumb i'm going by, according to my tuner is, at the WOT,

11-12 is the goal
13.5 to 16.5 good
>16.5 = lean
<12.5 = rich
19, 20, 22 too lean (not enough fuel)

Use OBD reader and run a log for all 4 o2 sensors and fuel trim , MAF, rpm, at hot idle.