[AWF10M5]

The pre cat sensor is 17908 which is the cheaper one with the longer wire.

How about the 2 o2 sensor on the downpipe? Is that bank 2? What is the part number and cheapest place to source these?

So the car only has these 4 o2 sensors right?

[!LEFTCOAST!]

Originally Posted by E63amg

The pre cat sensor is 17908 which is the cheaper one with the longer wire.

How about the 2 o2 sensor on the downpipe? Is that bank 2? What is the part number and cheapest place to source these?

So the car only has these 4 o2 sensors right?

.

[dyezak]

Jesus christ. This is a serious question? With RealOEM, ECS, Turner, etc all out there providing parts look-up capability. Amazon even returns the correct answer.

This is why this generation sucks...

[AWF10M5]

Originally Posted by dyezak

Jesus christ. This is a serious question? With RealOEM, ECS, Turner, etc all out there providing parts look-up capability. Amazon even returns the correct answer.

This is why this generation sucks...

Dont u have some viagra pills to pop old man? Your life must really suck if you are whining on a car forum on a sunday night on a holiday weekend.

Thx to the other guy btw ordered my sensors

[mweisdorfer]

You can get a Bosch Parts App for your iphone or android and look up the part numbers.

There are 2 pre cat and 2 post cat. After 100k you are on borrowed time with the pre-cats. Most people only replace the pre-cats. You should replace them in pairs. One monitors 1-3 and the other 4-6.

Up stream = pre-cat.

The post cats only monitor the pre-cats and make sure they are doing their job.

I have original post cats on my 335i and I have 140k.

[techwhiz]

Originally Posted by E63amg

The pre cat sensor is 17908 which is the cheaper one with the longer wire.

How about the 2 o2 sensor on the downpipe? Is that bank 2? What is the part number and cheapest place to source these?

So the car only has these 4 o2 sensors right?

There are four sensors. Look at RealOEM.
The ones that go bad are pre-cat.
You need two Bosch 17098 Oxygen Sensor, OE Type Fitment.
The difference between the part numbers is wire length.
The 17098 is the cheaper sensor with the long wires. DO NOT CUT THE WIRES!
Just coil the wire up and zip tie.

You will need an offset O2 socket to change them. There is no possibility of getting a standard O2 socket in there. You don't need to remove steering rack or any associated crap. You do need to remove under tray for better access.

[jwebb335xi]

Originally Posted by mweisdorfer

You can get a Bosch Parts App for your iphone or android and look up the part numbers.

There are 2 pre cat and 2 post cat. After 100k you are on borrowed time with the pre-cats. Most people only replace the pre-cats. You should replace them in pairs. One monitors 1-3 and the other 4-6.

Up stream = pre-cat.

The post cats only monitor the pre-cats and make sure they are doing their job.

I have original post cats on my 335i and I have 140k.

I did O2 and the valve cover. My AFRs are dead even and the car runs amazingly well at 99.5k. Easy job!!