M3 E46 Pre Cat O2 sensor replacement...

Edgy · Fri, Sep-25-2015, 12:54:53 AM

Good point. I have an aftermarket Agency Power section 1, Supersprint 2 and Agency Power 3, but no aftermarket headers.

Shouldn't affect this DIY, correct?

mpower22 · Fri, Sep-25-2015, 05:04:55 PM

That's right, it will not affect the install. I know a lot of people keep saying to access from the top, but I'm thinking you will have better access from the bottom, with the reinforcement plate removed but it is the most difficult sensor to access for sure.

BTB · Wed, Dec-30-2015, 07:08:44 PM

Bumping up this thread... Doing both my precat O2 sensors, I removed the egr valve and have the heat shield above the headers loose, but I can't get it out. It seems impossible without disconnecting this coolant line:

Can anyone tell me how they got their heat shield off? And if I have to disconnect the coolant line, is all of my coolant in the reservoir going to drain out?? That would be a pita

Edit:

After taking off the lower skid plate I realized that with my sgt headers all four oxygen sensors are pretty easily accessible under the car. Looks like I didn't need to loosen the heat shield in the first place!

206m3 · Thu, Jan-12-2017, 11:34:54 PM

Quote:

Originally Posted by ZiMMie

I personally use Bosch 15703 sensors. Just cut the old harness and mate it on the new sensor.

they are $25 each (or less) sensor, exact same narrowband sensor as the OE sensor.

Can anyone else vouch for this?

E36Alpine · Sun, Mar-04-2018, 03:38:51 AM

Quote:

Originally Posted by ZiMMie

I personally use Bosch 15703 sensors. Just cut the old harness and mate it on the new sensor.

they are $25 each (or less) sensor, exact same narrowband sensor as the OE sensor.

You have no idea what you are talking about. Anyone reading this do not do this.

E36Alpine · Sun, Mar-04-2018, 03:39:22 AM

Quote:

Originally Posted by 206m3

Can anyone else vouch for this?

Yes...DO NOT DO THIS.

TboneM3 · Sun, Mar-04-2018, 05:04:10 AM

BTB, why are you removing things? I just changed my pre cat o2s with a crow's foot and the only thing I did besides jacking the car up was removing the valve beauty cover to expose the harnesses for the O2s.

TboneM3 · Sun, Mar-04-2018, 05:04:52 AM

Quote:

Originally Posted by E36Alpine

Yes...DO NOT DO THIS.

Why? It's perfectly fine if you have decent wire splicing skills.

ZiMMie · Sun, Mar-04-2018, 06:37:38 AM

Quote:

Originally Posted by E36Alpine

You have no idea what you are talking about. Anyone reading this do not do this.

Ok Buddy..

Sent from my Redmi Note 4 using Tapatalk

delvin · Mon, Mar-12-2018, 05:55:19 AM

Quote:

Originally Posted by TboneM3

Why? It's perfectly fine if you have decent wire splicing skills.

Quote:

Originally Posted by ZiMMie

Ok Buddy..

Sent from my Redmi Note 4 using Tapatalk

So just to clarify they are the same sensor with a different plug? I just got a SES for pre cat O2's tonight and I have no problem wire splicing.

Fri, Sep-25-2015, 12:54:53 AM	#21
Edgy Constantly Learning M3 and M5 Owner Join Date: Jul 2002 Posts: 3,345 Reputation: 0 Location: Northern Virginia	Re: M3 E46 Pre Cat O2 sensor replacement... Good point. I have an aftermarket Agency Power section 1, Supersprint 2 and Agency Power 3, but no aftermarket headers. Shouldn't affect this DIY, correct? __________________ BLUE HEAVEN: Interlagos 2006 M3, AutoLogic tune, K&N CAI, Agency Power midpipes and exhaust, Fortune Auto coilovers, ///M Pedal Kit, UUC SSK. MRegistry listing here Le Mans 2002 M5, Black/Titanium, Rogue SSK, Dinan exhaust, PSS9 coilovers, Conforti/Shark tune. MRegistry listing here

Fri, Sep-25-2015, 05:04:55 PM	#22
mpower22 CPV O-Ring Guy Join Date: Dec 2002 Age: 37 Posts: 3,694 In the garage: '17 LR RANGE ROVER SPORT '03 BMW M3 Reputation: 0 Location: Maryland	Re: M3 E46 Pre Cat O2 sensor replacement... That's right, it will not affect the install. I know a lot of people keep saying to access from the top, but I'm thinking you will have better access from the bottom, with the reinforcement plate removed but it is the most difficult sensor to access for sure. __________________ ///M3 - Dream Car: Acquired 11/18/02 15-Year Forum Member 2003 M3Laguna Seca Blue/6MT ~~Black Leather Cloth Interior/Full [CSL] Exhaust~~ Original Owner, Custom Built - ~~PDC, Moonroof~~, ~~Bi-xenons (TFX)~~, ~~Brushed Aluminum Trim~~, ~~Bluetooth ULF~~ European - ~~Rotors (F&R)~~, ~~Bumper, Mirrors~~, Warning Triangle, ~~Console~~, ~~LSZ~~, ~~First Aid Kit~~, Fire Extinguisher ~~OE LED Conversion/Outer Ring Mod~~ \| ~~V1 Hardwired/Ashtray Display~~ \| ~~3M 35% Tint~~ \| ~~Intravee II~~, Diamond H600s, JL 10W3v3, HD900/5

Wed, Dec-30-2015, 07:08:44 PM	#23
BTB Registered User Join Date: Jun 2013 Posts: 1,917 In the garage: '99 Kawasaki Vulcan 1500 '05 Suzuki GSX-R750 '99 Kawasaki Ninja 250 '12 BMW ///M3 '03 BMW ///M3 Reputation: 0 Location: Orange County, California	M3 E46 Pre Cat O2 sensor replacement... Bumping up this thread... Doing both my precat O2 sensors, I removed the egr valve and have the heat shield above the headers loose, but I can't get it out. It seems impossible without disconnecting this coolant line: Can anyone tell me how they got their heat shield off? And if I have to disconnect the coolant line, is all of my coolant in the reservoir going to drain out?? That would be a pita Edit: After taking off the lower skid plate I realized that with my sgt headers all four oxygen sensors are pretty easily accessible under the car. Looks like I didn't need to loosen the heat shield in the first place! __________________ UIUC / TU Munich Mechanical Engineering 2018 2003 ///M3 6MT Coupe Imola Red/Black Napa, slicktop, manual seats My Journal Last edited by BTB; Wed, Dec-30-2015 at 08:10:47 PM.

Sun, Mar-04-2018, 05:04:10 AM	#27
TboneM3 YNWA Join Date: Oct 2009 Posts: 8,256 In the garage: '04 BMW M3 E46 Reputation: 0 Location: Socal	Re: M3 E46 Pre Cat O2 sensor replacement... BTB, why are you removing things? I just changed my pre cat o2s with a crow's foot and the only thing I did besides jacking the car up was removing the valve beauty cover to expose the harnesses for the O2s. __________________ /// 2004 SilberGrau M3 · Coupe · 6MT · slicktop · manual seats · zero options · ~3200lbs · JOURNAL _ Evolve-R Alpha N · Evolve CSL CF Airbox · Eventuri Scoop · Supersprint V1 stepped 2.5" · SS V1 S pipes 2.5" + 200 cell HFC · OE sect 2 · SCZA 2.5" sect 3 · Besian · RE pullies · WPC'd OE bearings · oil catch can · fan/SAP/washer delete · CSL battery GroundControl S/A Koni (Hyperco/Eibach 300/550) + tall RSMs · Hotchkis front sway (med) · rear strut bar · TMS camber & subframe plates · SPC alum rear camber arms · RE trans mounts · AKG poly subf/diff 95a · SDW RTAB · weighted ///M knob + ZHP alcantara boot + UUC DSSR + delrin bushing · Mason clutch pedal + brass bushing · TMS black pedals · delrin brake pedal bushing OE CSL trunk · Sportline 8S 18"x8.5/9.5" · MPSS 245/275 · APEX 75mm Studs · 12mm/10mm F/R spacers · Brembo 996 4 pot 36/40 345mm CSL & 28/30 328mm CSL · ZHP "712" rack · Pioneer/CDT/Eclipse/Kicker

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