Easiest way to replace precat O2 Sensor

[DBordello]

Howdy All,

My 2009 E92 M3 tossed an "increased emissions" error about a month ago. According to ODB II, it tossed an P2629 (Oxygen Sensor Pumping Current Trim Circuit/Open Bank 2 Sensor 1).

I took it to the dealer, and they estimated $1200 for the repair. However, I found the sensor on ebay for $60. And that brings us to today....

I know almost nothing about repairing cars. However, it sounded like the replacement was easy enough. I have my car up on two jack stands (driver side). I was able to locate the sensor, and remove it from the exhaust.

However, the problem is that I cannot access the connector. It is behind the large steel shield in the front of the car. Additionally, it is blocked by a cardboard-ish shield near the middle of the car.

Do I have to remove these shields to get access to the connector? There appears to be a lot of bolts involved in removing these.

Any suggestions? Assume I know nothing please

[s85e90]

Is it the driver or pass side? You need to removed that plastic/felt shield. You may be able to get it out then. You may not need to drop the front metal skid plate. If needed you can just drop the back of it to get your hands on the o2 connections. Once things are apart you should be able to visibly see and trace the wires to the connector to unplug it. Good luck!

[WayneM3]

There is a chance that you might be able to do the driver's side with just removing the center cardboard shield under the transmission but it will be tricky to unclip the connector and plug the new one in. There is zero chance of doing the passenger side one that way because one of the bolts holding the connector is directly blocked by the metal shield. It is pretty easy to remove the metal shield with the large bolts and the 3 (or 4) small ones at the front but don't forget the one right in the middle of the jacking puck. The job will be MUCH easier with that plate out. There is an official BMW procedure to tighten those big bolts back but I just make them pretty tight and I have never had an issue.

[DBordello]

It is the driver side sensor. I can see the connector, I just can't get to it.

I am going to attempt to remove the felt shield. It seems it is connected by a ton of bolts though.

[BPMSport]

You have to remove the bottom panels. Don't use a $60 ebay sensor. Get it from amazon, ecs, or rock auto. It's roughly $150-200 for the sensor. Takes about an hour or two and you should remove the bottom panels. Lots of bolts. I would also replace the other one while you're in there given you have an 08.

[Dave07997S]

Listen to Mike...you get that $60 sensor and you will be doing it again. Get the OEM BMW sensor, it does matter and as Mike says its about $175-225.00. Tischler sells the part for $225.00. I think you can find one on Amazon for around $175.00.

Dealer wants $1200 for this..ridiculous.

Dave

[DBordello]

Well, that wasn't so bad. I took the felt shield off, and was able reach the connector. Some of the bolts on the felt shield are hard to get to, I need to find a 8mm socket driver.


I fully agree with everybody regarding eBay. I purchased it at a moment of weakness. Now, however, if the fault pops up again, I won't know if it was the sensor or another problem. Hopefully this one holds on for a while, and I can replace both of them further down the road.

Thanks for the advice.

[WayneM3]

I bought my genuine Bosch replacement O2 sensors from Amazon for $100 each (+ tax) but I see they are out of stock now and the other sellers want quite a bit more.

[DBordello]

Quick update. So far, everything is going well. I cleared the fault with an ODB II reader, and it hasn't re-emerged after ~70 miles. However, I am not going to be confident it is fixed until 100+ miles. I am not sure how long it takes to re-trigger.

[M3PO]

Yeah, I've heard those $60 "Bosch" sensors are fake.