O2 Sensor Replacement - Question

Hey Fellas,

I just replaced the Bank 1, Sensor 1 (Front) on my car. Attached is the picture of how it looked after taking it out at 105K - pretty dark!

Though I was successful changing the front sensor I couldn't get to the rear one - Bank 2, Sensor 1. The oxygen sensor was inaccessible due the sensor cover on top. It's a metal plate that is held by two screws which are pointing downward and are difficult to access. I thought I might be able to get to them from underneath the car so put her up on ramps and tried for about an hour but with no luck. I could see the screws from underneath but still couldn't make out how to reach them as the space isn't enough for a wrench to get there.

Anybody has any insight on it as to what would be the best way to get them out. Without removing that sensor cover plate it's not possible to remove the sensor. I was disappointed to put back everything without replacing the other sensor and that too just coz of those 2 darn screws!

How does BMW expects someone to replace them?

Any help appreciated!

IIRC, I did most of the work from underneath the car. It's really tight, but it's possible to twist one arm through the front suspension to loosen the bolts that hold the cover.

Originally Posted by gp500

IIRC, I did most of the work from underneath the car. It's really tight, but it's possible to twist one arm through the front suspension to loosen the bolts that hold the cover.

I guess the key here would be to have a long handle ratchet as I had trouble reaching it or may be hands are too small!
By "through the front suspension" do you mean I will have to remove the splash cover and the front passenger side wheel to access it?

I also have an '07 3.0si and have a SES light on. My code reader says that the bank 2 sensor is the problem. I see the metal shield that covers the back 3 sensors but I think you can still remove the sensor without removing the cover. Has anyone else done this and if so, did you have to remove the cover?

Subscribing because I'm sure ill be here soon. After all my 09 is at 107k.

Technically o2 sensors are warrantied to 150k, depending on year, in California but its easier said than done

Originally Posted by mhughett

I also have an '07 3.0si and have a SES light on. My code reader says that the bank 2 sensor is the problem. I see the metal shield that covers the back 3 sensors but I think you can still remove the sensor without removing the cover. Has anyone else done this and if so, did you have to remove the cover?

Well, I completed the replacement of my bank 2 O2 sensor last Friday. It was NOT easy and if it weren't for some special tools I own, it would have been much harder. Here is a summary of how it is done:

1. Take out the "snorkel" in the front. You need to remove this so that you can get the plastic cover off the engine. The cover is removed with 4 5mm hex screws.
2. I used a crows-foot type O2 sensor tool. As a result I was forced to move the metal plate in front of the sensor.
3. Once you have the cover removed, follow the sensor wire back from the sensor to the connector. Once you find which connector goes to the bank 2 sensor, disconnect it as it has to be disconnected before you tackle the sensor.
4. There are two E-torx screws holding on the metal plate. The one on the right isn't too hard to get to except that one of the high-pressure A/C lines is in the way. Nevertheless, the screw on the right isn't too bad to remove. It's a slow process but I benefitted from using a new tool I got at Harbor Freight last week. It's called a "sidewinder ratchet". It works like a normal ratchet but it also has a T on the end of the handle. Once you get the screw loosened, you can turn the "T" and it turns the screw without having to move the handle. Very clever and useful in situations where movement is limited.
5. The screw on the left side is almost hidden from the top. If you remove the cowling that includes the cabin air filter, you can see it (barely) but I found the best way to get to it was by feel bringing the ratchet in from the right, parallel to the plate. I loosened it with the sidewinder and only loosened it half way out. The reason I didn't completely remove it is that I was afraid that I would have trouble lining up and starting the screws since you can't really see anything down there.
6. By loosening the left screw, you can move the plate just enough to attache the O2 sensor tool. I also attached a universal adapter and about 15" of extensions. You can't get a straight shot at the O2 sensor to loosen it. You pretty much have to use the universal.
7. Once you loosen the O2 sensor, you can twist out the sensor by hand but it helps to twist the chord at the same time in the same direction as the sensor comes out.
8. Everything goes back in the opposite of the removal methods. I was glad I left the left screw semi-attached as I used my sidewinder to screw it in the rest of the way. The right hand screw had to be started by feel only but with the left side already in it made it much easier to line up.

FYI, I tried to get to the screws and sensor from below with my car on jackstands. There was no way I could reach far enough from the opening below so I quickly realized that the only way to do it was from above. I reset my SES light with the Bavarian Technic cable and the light hasn't returned since. I hope this helps anyone else who wants to give it a go.