BMW M3 Forum
BMW M3 Forum BMW M3 Gallery BMW M3 Reviews BMW M3 Social Groups BMW M3 Chat M3Forum Sponsors >>

Mobile M3forum
Go Back   BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X) > BMW M3 Discussions > E46 M3 (2001-2006)
Tire Rack Buy Winter Tires Now!
Not a member? Register Now!
Register Gallery All Albums Garage Search Today's Posts Mark Forums Read Calendar FAQ

E46 M3 (2001-2006) Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006.

Thread Tools Display Modes
Old Mon, Dec-12-2016, 03:05:04 AM   #21
Join Date: Nov 2013
Posts: 2
Reputation: 0 mderenthal is on a distinguished road
Location: Orlando

United States

Default Re: Pre-Cat O2 sensor DIY?

Just finished replacing all O2 sensors (and leaky CPV gasket while down there) and I'd estimate this job takes about 1.5 hours of actual work, and about twice that much time to figure out how to access everything. Second time through will be much easier. (I accessed the bank 2 pre-cat from underneath).

Last edited by mderenthal; Mon, Dec-12-2016 at 03:09:20 AM.
Jump to top mderenthal is offline   Reply With Quote
Sponsored Links
Register now and remove these ads
Old Sat, Mar-31-2018, 10:27:56 PM   #22
Alex Sol
Registered User
Alex Sol's Avatar
Join Date: Jul 2014
Posts: 55
Reputation: 0 Alex Sol is on a distinguished road

United States

Default Re: Pre-Cat O2 sensor DIY?

Just completed the replacement of o2 sensor and wish to add some comments from my experience.

I had bank 2 sensor 1 go and figured i'd order the two pre cat sensors and replace at same time.

There are some diy on this subject but it seems some of them were deleted.

I started with remove fan shroud which is back off the 3 plastic screws (they are just straight so no threads and easy to drop) I did find one later in the lower plastic shroud that has to be removed.

remove the strut bar with the 4 x 13mm bolts

Then the cover where you first remove the oil filler cap and the six (I only have 5) 10mm bolts.

Removed the cabin air filter and the water catch tray below it. Unhook the main power that goes to the jumper and another wire. Remove this before the cover to easily access everything.

Then carefully removed the plastic cover that covers two sensor connections but these are for the post cat 02 sensors.

The pre cat 02 sensors are connected closer to the fire wall.

Then removed the plastic shroud under car with the six x 8mm screws

Then removed the aluminum shroud with the 11 or so 16mm bolts and 3 x 8mm screws.

Then removed the heat shield that is held on by 3 x 13mm and one 10mm bolt

Removed the hose from the coolant tank, removed coolant first using a Motive extractor. Then removed the secondary air injector piece with two x 10mm nuts

Once I had all this in hand, I could remove the bank 1 02 sensor from the top with my crow foot 02 sensor tool. I have a 7pc set.

Then went underneath using the extension technique with the 'reverse' drive to loosen the bank 2 sensor. That work well and just popped then I could unscrew by hand.

Replacement was reverse.

One thing I learned is that the two sensors have different connectors only slightly and so they cannot be reversed... dummy proof except when you have two of the same sensor then you are the dummy!! so make sure to but the two different patterns.

Other tip I could add is to have the car up safely and on jack stands and jacks as back up. Don't want to die saving $60 bucks...

Hope that helps.
1991 Guards Red Porsche 964 C2
2009 335d
2003 m3
Jump to top Alex Sol is offline   Reply With Quote


diy, precat, sensor

Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump

All times are GMT. The time now is 04:35:07 PM.

Powered by vBulletin® Version 3.8.6
Copyright ©2000 - 2018, Jelsoft Enterprises Ltd. and is in no way sponsored, endorsed or affiliated by or with BMW NA / BMW AG or any of it's subsidiaries or vendors.
BMW and M3 (E90 M3 | E92 M3 | E93 M3 | E46 M3 | E36 M3 | E30 M3) are registered trademarks of BMW AG.
M3Forum Terms of Service
Copyright 1999-2017
Discussing Pre-Cat O2 sensor DIY? in the E46 M3 (2001-2006) Forum - Engine: S54 - Max Hp: 333 hp at 7,900 rpm / 262 lb/ft at 4,900 rpm
Total Produced: 45,000+ - Years Produced: 2001 to 2006. at BMW M3 (E30 M3 | E36 M3 | E46 M3 | E92 M3 | F80/X)