BMW E46 Fanatics Forum banner

1 - 18 of 18 Posts

·
Registered
Joined
·
31 Posts
Discussion Starter #1
I have a 2000 330i e46 just got back from the shop and they quoted me $1300 for all o2 sensors to be replaced. Figured I***8217;d save money and do it my self. So I started replacing my pre cat sensors and found that there***8217;s no sensors there at all.
And the whole thing is missing for both sensors.
Can someone please tell me what this means? What***8217;s my next step? Take it to the mechanics ?
 

Attachments

·
Registered
Joined
·
385 Posts
If you can take some better pictures for the exhaust manifold so we can see what type of exhaust manifold or headers you have.

Sent from my SM-J415F using Tapatalk
 

·
Registered
Joined
·
31 Posts
Discussion Starter #3
If you can take some better pictures for the exhaust manifold so we can see what type of exhaust manifold or headers you have.

Sent from my SM-J415F using Tapatalk
Thanks infoboy and sorry about the pictures I***8217;m not sure where else to take them.I just bought the car about a month ago, The infamous p0174 and p0171 codes came up, the engine is running lean with a 27.3% fuel trim. I checked for vacuum leaks and couldn't find any so i decided to take it to a shop and they said it was the o2 sensors.In all the YouTube videos for precat sensors they get replaced there but my car doesn't have the harness' and where the sensors would be located.
 

·
Registered
2004 325i automagic
Joined
·
2,012 Posts
Get a bright flashlight and light up the space under the flat heat shield sticking out from the side of the engine where the exhaust manifolds head down. Can't tell what is under there or not. To get more room, remove the SAP mounting bracket and the washer fluid reservior.

Are you located, UK, Thailand, etc, by chance?? You have a right hand drive car I notice, so the O2 sensor layout will be different that the more typical LHD setup on most e46 writeups you will find online. I think the bank 2 sensor is trickier to access, due to steering column. There was a thread about doing this on here a while ago, but you might find more info on a UK forum.

Edit: here is that thread. It has some good pictures and in post 27 a link to a RHD writeup:
https://forum.e46fanatics.com/showthread.php?t=1244531


Fwiw, I recently had one of my pre-cat O2 sensors go bad and peg lean at 27% fuel trim. DME was dumping so much fuel in that bank that I could smell fuel at idle. The other bank was normal, and they only had arpund 75k miles on them. Changed both O2 sensors, and kept the good one as a spare.

Since the car is new to you, make sure the cooling system is up to date as that is a major weakness. The expansion tank is pressurized and old one like to crack. Overheats can easily blow headgaskets, crack heads, and ruin headbolt threads in the block.

Check out the cooling system refresh guide:
https://forum.e46fanatics.com/showthread.php?t=914109
 

·
Registered
Joined
·
10,029 Posts
See my post at bimmerforums. Those codes are classic for vacuum leaks. So, the problem is on the other side of the engine. Likely the intake boots (large rubber hoses that run from the air cleaner box to the engine) have cracks.

Go to www.realoem.com and enter the last 7 characters of your car’s vehicle identification number. Hit enter and bookmark the page. Click on the engine icon to find the part numbers. Run away from that shop.


Sent from my iPhone using E46Fanatics
 

·
Premium Member
2003 330cic, 2003 325iT
Joined
·
3,882 Posts
I have a 2000 330i e46 just got back from the shop and they quoted me $1300 for all o2 sensors to be replaced. Figured I'd save money and do it my self. So I started replacing my pre cat sensors and found that there's no sensors there at all.
And the whole thing is missing for both sensors.
Can someone please tell me what this means? What's my next step? Take it to the mechanics ?
Also, remove the engine covers and take a picture. I am curious if the sensor connectors are there
 

·
Registered
2004 325i automagic
Joined
·
2,012 Posts
Thanks infoboy and sorry about the pictures I'm not sure where else to take them.I just bought the car about a month ago, The infamous p0174 and p0171 codes came up, the engine is running lean with a 27.3% fuel trim. I checked for vacuum leaks and couldn't find any so i decided to take it to a shop and they said it was the o2 sensors.In all the YouTube videos for precat sensors they get replaced there but my car doesn't have the harness' and where the sensors would be located.
How did you check for vacuum leaks? Aside from obvious tears in the intake boots (especially the lower boot where it branches off in two), its best to do a smoke test. Remove all the plastic covers and the cabin air filter housing as well.

Check out:
https://e46fanatics.com/forum/showthread.php?t=1261077
 

·
Registered
Joined
·
31 Posts
Discussion Starter #11
Hm interesting I did find two of them but I thinking they***8217;re the post cat?
Also could be wrong
The first pic is taken from above and the second pic from under the car
 

·
Registered
2004 325i automagic
Joined
·
2,012 Posts
Thanks but mine doesn't look like that ***x1f615;
You might have catless exhaust headers from the looks of your second picture in post #14 and in post 12. You can get a better look from underneath the car looking upward (edit ... just saw picture in post 13 ... I don't see a catalytic converter on bank 2 & cant really see bank 1). You might get a better view of bank 1 looking from the a/c compressor area.

If these really catless headers, then the two visible O2 sensor connectors attached to the fuel rail (which are normally the post-cat O2 sensors) might be the only O2 sensors on the car.


Also, remove the engine covers and take a picture. I am curious if the sensor connectors are there
?
So take off the cover and look ... the one remaining cover. But relative to Paraklas' picture it doesn't look like you have cats.
 

·
Registered
2004 325i automagic
Joined
·
2,012 Posts
Hey these are the two best ones I could take from under the car looking up,
Catless headers, maybe, but the car is reading the o2 sensors voltages if I'm not mistaken
Any chance there is an emulator installed somewhere? If you have an inspection mirror you can get a better look at bank 1. Also, remove the washer fluid reservior and you will have much more room to look & take pictures from that vantage point.

We can see two O2 sensors in the pictures so far ... label the two O2 sensor connections on the fuel rail so you don't mix them up and then follow them back ward to see where they lead to. Or disconnect one at a time and trace each wire back to its sensor one after the other. If there are other O2 sensors there is not much room closer to the engine, so perhaps look further back toward the rear.
 
1 - 18 of 18 Posts
Top