Hi all-

So I got a SES for code P0151--heater circuit voltage low, Bank 2/Sensor 1. OK, I thought, it's a bad O2 sensor--easy enough. Found a DIY on E46fanatics for the same sensor, albeit by a non-M owner, here (http://forum.e46fanatics.com/showthread.php?t=313882).

Ordered both pre-cat sensors from Bimmerparts for $292 total shipped, which was far better than Advance Auto's $225 per sensor (Bosch OEM); didn't even call the local stealer!

Before attempting the job, I poked and prodded around in the engine bay a bit, and I could not for the life of me see those darn sensors in the small gap between the exhaust manifold heat shield and all the other wires and crap down there. I suppose I should have stopped then and there and done some long, hard thinking--but I was anxious to get rid of this intermittent code and presumably driveability problems.

Using those instructions, therefore, I took out the microfilter, microfilter housing, and engine cover (and proceeded to break the PCV line :mad :mad :mad), only to find that sure enough, that damn heat shield is obstructing any real access to the O2 sensors. Now, I could see the bank 2 sensor, but even if I could access it, I'd need a super-long extension (12" +)--as the DIY sure enough states--but even then, it'd be a stretch. I think our S54s have considerably different configurations in that area than the M54s. How would I get the new O2 sensor on, let alone threading it in by hand?! I can't possibly fit my hand in that 2" space.

It started to rain (I hate summers here and the unpredictable thunderstorms that come with them! :mad) so I had to quickly put all my crap back together, but now I'm just plain frustrated. My Umnitza DDEs on the driver side also blew up this weekend, and I spent all morning trying to figure out how to splice in a new ballast, so I guess you could say it's been a very unproductive and aggravating day (if anybody has any advice to that end, it would be welcome as well).

Any advice to access and replace these pre-cat O2 sensors would be much appreciated!

Thanks.

I followed this when I did my headers..

http://www.m3forum.net/m3forum/showthread.php?t=151391&highlight=header+DIY

Thanks Jeff. Coincidentally, I was just reading that when you posted! I'd read it before but forgot all about it, and now a light bulb just went off and I realized oops, dummy, I needed to remove the heat shield. I think I was a bit intimidated by it since it sliced open my hand (well, I sliced open my hand on it...).

Is that the best way, remove the heat shield? My friend also suggested tackling it from the bottom, i.e. jacking it up. But my car is a PITA to jack up (impossible without a low-pro jack) and it might even be harder to get up into the headers from that angle.

Is that the best way, remove the heat shield? My friend also suggested tackling it from the bottom, i.e. jacking it up. But my car is a PITA to jack up (impossible without a low-pro jack) and it might even be harder to get up into the headers from that angle.

Yeah get them from the top of the car.

Here's a picture of my car with one of the heat shields removed. You can see both 02 sensors, so I would stick to getting them from above

http://i57.photobucket.com/albums/g206/gameshot/DSCN0666.jpg

Yeah get them from the top of the car.

Here's a picture of my car with one of the heat shields removed. You can see both 02 sensors, so I would stick to getting them from above

http://i57.photobucket.com/albums/g206/gameshot/DSCN0666.jpg

Awesome, thanks for the pic. How long do you estimate of an extension I'll need to get in that space to get a 22mm O2 sensor socket onto those sensors?

I never used an 02 sensor socket. Lol. I just stuck my hand down there and used a wrench.

So now I have everything apart again, including the upper heat shield, and I can indeed see sensor #1 (Cyls 1-3). However, until just now, I could not see sensor #2 (Cyls. 4-6). Shining a flashlight in there, I can see it, but it appears to be way far back there. I don't know how I'd get anything on it, let alone any leverage. #1 looks pretty daunting, too.

Perhaps it's worth mentioning that I have SuperSprint headers; do they change the layout of the O2 sensors?

Any tips?

Thanks.

I'm not sure if this would apply but take a look.

file:///Users/rbarke/Desktop/Car/DIY:Tech/DO%20IT%20Yourself.webarchive

Oops sorry didn't read your entire OP. Disregard.

So now I have everything apart again, including the upper heat shield, and I can indeed see sensor #1 (Cyls 1-3). However, until just now, I could not see sensor #2 (Cyls. 4-6). Shining a flashlight in there, I can see it, but it appears to be way far back there. I don't know how I'd get anything on it, let alone any leverage. #1 looks pretty daunting, too.

Perhaps it's worth mentioning that I have SuperSprint headers; do they change the layout of the O2 sensors?

Any tips?

Thanks.


I have SuperSprint headers as well. I can't remember exactly how I put back in my 02 sensors. lol.

You might need to come up from the bottom. Just drive up on blocks so you can get a jack underneath (that's what I do)

I have SuperSprint headers as well. I can't remember exactly how I put back in my 02 sensors. lol.

You might need to come up from the bottom. Just drive up on blocks so you can get a jack underneath (that's what I do)

Yep, I got that tip from a couple M3forum members as well; I think I've been approaching it wrong the whole time. Spent 5 hours on it today, and all I have to show for it is half my engine apart and scratches, bruises, and dirt on my hands and arms. :lol Funny, but also profoundly maddening. :mad

I think that were I removing the headers it would be different, but unless I want to remove all the wiring, the coolant reservoir, etc. that the headers DIY mentioned, it's probably easier to come from the bottom. I ended up removing the EGR valve, couple coolant hoses, the exhaust manifold heat shield, etc., so now I probably have air bubbles in my cooling system to worry about. :rolleyes

Thanks for the tips; I'll be sure to report back tomorrow.