1986 325es o2 Oxygen Sensor Location and Replacement

[tonerrrr]

I know this has been covered before many times BUT after researching it and saying "ok I'm ready to do this" I find myself in my engine bay wondering where the f my o2 sensor is!



The usual spot is right after/around the header area however on my 325es, it was way farther down the line.



After looking online and seeing everyone say it was near the header, I thought my car just didn't have one...which is why I'm writing this post...for us 325e guys ;)

I purchased the 1990 Ford Mustang 5.0 Sensor Bosch Part #13942 (http://www.ebay.com/itm/ws/eBayISAPI...m=130560218073) and it looked a hell of a lot better than the one I pulled out(new on left):



Since the plug for the Mustang sensor doesn't match, you need to attach it to your old o2 sensor's plug. I've read online saying to leave plenty of wire, I just left what's shown here. Once you get under the car, it's apparent you don't really need/want to add 8"+ of wire, there's just nowhere for it to go.



After splicing together:



Final electrical tape covering:



Installed:




I hope this comes up in searches for someone who's looking for this info like I was. There are plenty of other threads out there about wires and what not, basically since my car had 2 whites and 1 black, it was a straight forward white>white, white>white, and black>black for me. It's understood the white wires do not have a polarity, so connect either white to either white.

Side note: I decided to change my o2 sensor after reading about how it could affect engine pulsing while accelerating, which is what my engine did, very very subtle but annoying none the less. After installing this new one, I took it for a test drive and sure enough it seemed like the car was running a bit better. I'll have to wait and see if there are any MPG gains. Either way, I've read this part should be replaced every 60k so, in my experience with used cars, don't take anything for granted.

With my car, which supposedly had 170k when sold to me, I plan on replacing all the sensors bad or not. I figure if I replace all this small crap I can have piece of mind since who knows what the PO did/replaced... Also like mentioned before as well, sorry if this was covered for a 325e, but I couldn't find any mention of it.

[CW325]

good write up, whats the advantage of running a mustang o2 sensor?

[tonerrrr]

Thanks, Paying $100 less than a "BMW" o2 sensor :D no actual fitting plug though, hence the splice, but no other differences that I'm aware of.

[CW325]

i didnt even look how cheap these go for! thanks for the info

[MR 325]

That's the standard location for the Eta o2 sensor. The i cars have them in the downpipe.

[Cronopoulos]

Thanks for the write up!

[cabriodster87]

That's the standard location for the Eta o2 sensor. The i cars have them in the downpipe.

That explanes why all the short e-bay headders have the O2 fitting there. China developed a copy from an Eta exhaust and called it "fits i cars". lol
http://www.ebay.com/itm/BMW-E30-325i...tem&hash=item3 I also have a mustang O2 but didn't use it because i thought a splice wouldn't last long.

[tonerrrr]

eBay ftw! Haha

I'll report back if my splice job doesn't hold up.

[stillkotd]

Is there a bosch 4-wire o2 sensor that can be spliced? I like this "save $100" idea...

[tonerrrr]

Is there a bosch 4-wire o2 sensor that can be spliced? I like this "save $100" idea...

The same one in the eBay link I posted, the "mustang" one would work. You can wire it together, the 4th is a ground for you.

Check here for a write up from someone with a 1989 i engine: http://e30world.com/fuel/BMW-E30-Oxy...or-Replacement

In his write up: "5. If you have the old 3 wire BMW sensor, then it's a direct splice to the Ford wires. Black to black, and 1 white to 1 white. I believe that it does not matter which white wire goes to which lead, as they're just for heating. If you have the old 4 wire BMW sensor, then the fourth grey wire is a ground. just ground it to the chassis, or to the new O2 sensor itself. I used wire screws to make the connection, you can use bullet connectors, heat shrinkwrap, etc etc."

[stillkotd]

Sweet, thanks!