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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 3 Series / 4 Series > E36 (1991 - 1999)

E36 (1991 - 1999)
The E36 chassis 3-Series BMW was a huge hit among driving enthusiasts from the first moment the car hit the pavement. The E36 won numerous awards over the years it was produced and is still a favorite of many BMW enthusiasts to this day! -- View the E36 Wiki

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  #1  
Old 11-04-2008, 03:12 PM
bayerischern bayerischern is offline
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Unhappy Can't find O2 sensors on my 98 323is

I have a 98 323is coupe with 90k on it. It's time to change the sensors out. I have replaced the two that are on the cat itself. I know that there are two on the headers, because that's where I have seen them all over, and every forum I have looked, every parts catalog says they are there. But when put the car in the air, and pulled off the cover on the engine by the intake manifold...there are no pre-existing O2 sensors! And on the headers, there are places for them, but they are plugged with a bolt...is a 98 323is supposed to be like that? My CEL is on and when I ran the diagnostic it says that there is a deficiency in bank one...

My dad is a retired BMW Factory Tech and even he can't figure out why there wouldn't be pre existing O2 sensors there unless A) they were removed for whatever reason (I bought this car used 2 years ago btw) or B) the car is not made to have more than 2...which makes no sense because its a 98...so it should be OBDII which means 4 sensors, right?

Someone help me out here....
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  #2  
Old 11-04-2008, 03:23 PM
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diptenkrom diptenkrom is offline
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can you find that someone put in o2 simulators? that would make some kind of sense...
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  #3  
Old 11-04-2008, 07:28 PM
bayerischern bayerischern is offline
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Well...I've so far seen in several forums that these cars have 4 sensors...but they're all on m54 (328) motors...none for the 323 (M52) The 323is seems to be a unique car as far as parts go, unlike other older BMWs where you could interchange parts...you can with this one. My 91 325is would except the MAF unit from a 535i and same with the throttle body, etc. Not quite the same on this one. I miss OBDI. God damn.

I used my VIN at my local BMW dealer to look up parts for my car. It says that there are only 2 sensors for it that go on the cat itself....so then why would my new cat already be shot, or why would I get a check engine code that states "catalytic deficiency in bank one"?

My buddy has the same year and model...I'll have to compare his with mine...if his car has O2 sensors on the exhaust manifold...then I need to figure out what recalls were done on the car....
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  #4  
Old 11-06-2008, 03:13 PM
Creek Dweller Creek Dweller is offline
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I have a 1998 323is and changed out the O2 sensors (2) each. Located (1) pre cat (1) post cat. Hope this helps it was a easy job. The sensors both have the same length elect. lines and one is too long, bundle and hide the longer one the best you can to prevent rock damage. Hope this helps.
Michael
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  #5  
Old 11-06-2008, 04:31 PM
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drivinfaster drivinfaster is offline
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are you sure you are not talking about the exhaust port plugs?? there are two manifolds, the first bank (cyl 1,2,& 3), and the second bank (4,5,& 6). the pre-cat O2 sensors should be in front of the cats, close to the floorpan. if you don't know they're there, you could very easily overlook them.

oh, and pics would be helpful too. (we love pics....)

drivinfaster
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  #6  
Old 05-11-2011, 05:33 AM
Molon_Labe Molon_Labe is offline
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Mein Auto: 1999 BMW 323is
Reviving a very old thread, but I've run into this same problem.
I've got a 1999 (e36) 323is. My CEL came on and I found that I need to have a pre-cat O2 sensor replaced.
I did plenty of research as I'd never done this before. I found out the part number and everything. I got 2 sensors by Bosch.
The part number is 13884. I just got under my car this morning to get it done and found no existing pre-cat O2 sensors.
I am quite perplexed.
Maybe someone has some more insight regarding this issue?
Thanks!
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  #7  
Old 05-11-2011, 09:08 AM
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ZeGerman ZeGerman is offline
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You'll just have to look again.
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  #8  
Old 05-11-2011, 09:55 AM
Molon_Labe Molon_Labe is offline
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Here's a diagram of where my pre-cat sensors are:
http://realoem.com/bmw/showparts.do?...71&hg=11&fg=50

I was under the car less than 20 minutes ago.
I saw where they should be and they weren't there. The holes in both headers were just bolted.
The two no.6 brackets in that diagram are located along the fuel rail and I could see the guide shield (3) from under the car.
All the hardware is there, but it's like the sensors are just missing.
The 2 post-cat sensors are there, but the code I'm getting on my Peake fault code tool is 11-E5 (Table 11, Code E5).
It's defined as: "PreCat O2 Sensor Response Time, Cyl #1-3."
Resource: http://www.peakeresearch.com/manuals...201.0%20NA.pdf
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  #9  
Old 05-14-2011, 12:23 AM
chopsim323 chopsim323 is offline
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Mein Auto: 1998 323i SE
My 1998 323i se only has 2 O2 sensors both on the manifold. I think our European cars are different to yours.
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  #10  
Old 05-14-2011, 05:58 AM
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drivinfaster drivinfaster is offline
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Quote:
Originally Posted by ZeGerman View Post
You'll just have to look again.
^this...

they're there. you're looking at the port plugs onthe manifolds if you see 'blanks'. look around and behind the manifolds and you should see them.

mine is pre-obd2 so i only have the one, and it's not on the manifolds, but at the front of the cat close to the floor. wuddapainindabutt...yours should be a bit easier, though.


df
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  #11  
Old 05-06-2013, 09:08 AM
Verstappen Verstappen is offline
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98 323is With no pre cat O2 Sensors!

This is a very old post but I wanted to chime in, I just bought a 98 323is and while I was under the car yesterday I noticed that my car does not have O2 sensors on the exhaust manifolds, the ports are blocked with bolts and it only has the las two sensors on the cat itself.

I looked for the wiring and conectors for the front ones in case someone decided to get rid of them in the past and tuck the wiring away but I did NOT see them anywhere, a friend told me the two conectors for the manifold sensors are towards the top of the engine on the left side, and after calling pelicanparts they told me the conectors should be near the conectors for the sensors in the cat (bottom of the car).

Anyone found out whats going on with our cars not having sensors on the headers?
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  #12  
Old 04-25-2014, 03:51 AM
noyz25 noyz25 is offline
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Any progress here guys? I have codes also and just found this post.
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  #13  
Old 04-25-2014, 07:55 AM
hnaz hnaz is offline
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I hope this helps:

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  #14  
Old 04-25-2014, 08:45 AM
kptaylor kptaylor is offline
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As said much earlier, there are just two O2 sensors on our cars as compared to the M3 and 328(?). Replace one or both and your codes should go away if they're O2 related.
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  #15  
Old 04-25-2014, 06:33 PM
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drivinfaster drivinfaster is offline
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wow,...blast from the past.....


you need to know which o2 sensor codes you are chasing, first.

a code definition is the best way to get pointed in the right direction because a slow reacting code is different from an at limits threshold, and completely different from a heater circuit code,....but they're all "o2 sensor codes'.....







df
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  #16  
Old 04-26-2014, 01:26 PM
noyz25 noyz25 is offline
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I have code P0134 and P0141.
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  #17  
Old 04-26-2014, 06:51 PM
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drivinfaster drivinfaster is offline
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po134 is no activity sensor 1 bank 1. meaning the signal wire is broken, or shorted to ground, or the sensor is deader than a doorknob, but the pcm is not seeing anyone home here.

this would be bank 1, sensor 1, which is the front most exhaust manifold primary sensor.


po141 is a heated circuit malfunction, bank 1 sensor 2. this is the sort of thing that has brought many diy'ers down to their knees when the replacement sensor did not fix the code.

i mean, i *could* be the sensor, but there is also a relay involved, which is also prone to failure.

they are orange, but depending upon who you ask, they have a different location in the relay box. and not all orange relay are o2 sensor heater circuits.




df
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