Pre-Cat O2 Oxygen Sensor issue - solved
07-14-2014, 07:27 AM
#1
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Pre-Cat O2 Oxygen Sensor issue - solved
Yes, I know I'm obviously not a master mechanic, but there are a few things that can slow you up from doing an O2 Sensor change on a 2004 525i, M54.
1. Be sure you get the right sensors .. the ones at the top of the engine have an oval connector, and Bank 1 is black and Bank 2 is gray. (I ordered the wrong ones and had to return them.)
2. You have to get both engine covers off. The first one (facing engine, on left) is easy enough, but the back bolt that holds the right (or middle-ish) engine cover is not accessible unless you remove the in-cabin air assembly.
Removing the assembly is not hard, but you will need a torx (or allen wrench that I sometimes use on Torx when Torx bits are not handy!) a 13mm socket, and a smaller flat-head screwdriver.
Remove the air filters with the metal bar that springs off, and then turn the 13mm holding it a half turn or so on passenger and driver sides. Slide the middle plastic keeper that holds the left and right filter mounts together.
Turn off all the 13mm nuts half turnl there are 4 or so of them each side, and then use a Torx to remove one (each side) on the front side of the assembly.
Take off all that stuff, and then you come to the center hose mounts. Here you will see a very "tricky" fastener that I've never seen before - no slot head, no hex head or Torx, just a flat pin! There is one on each side. Pry that pin up with a small flat-head screwdriver, be sure not to lose it. Once out, there is a grommet-looking round thing you have also pry out.
Once you have those items out, you can pull the hose keeper forward and finagle the hoses out of it and remove the keeper. Now you can see the back bolt for the engine cover and remove it to finally see the O2 sensor connectors and wires. Oh, and using a O2 sensor remover (22MM) works great, just be sure that the ear for the 1/4" socket extender is closer to you. Replacing the sensors is very easy, then put everything back.
Oh, I forgot, there are rubber pieces that just sit on other side of the filter assembly that just hold themselves in. Just remember which way they go.
I know this description probably seems very complicated, but I promise, once you start into it is very, very simple! If you are even considering doing your own 02 change, you'll have absolutely no trouble.
I hope it helps.
1. Be sure you get the right sensors .. the ones at the top of the engine have an oval connector, and Bank 1 is black and Bank 2 is gray. (I ordered the wrong ones and had to return them.)
2. You have to get both engine covers off. The first one (facing engine, on left) is easy enough, but the back bolt that holds the right (or middle-ish) engine cover is not accessible unless you remove the in-cabin air assembly.
Removing the assembly is not hard, but you will need a torx (or allen wrench that I sometimes use on Torx when Torx bits are not handy!) a 13mm socket, and a smaller flat-head screwdriver.
Remove the air filters with the metal bar that springs off, and then turn the 13mm holding it a half turn or so on passenger and driver sides. Slide the middle plastic keeper that holds the left and right filter mounts together.
Turn off all the 13mm nuts half turnl there are 4 or so of them each side, and then use a Torx to remove one (each side) on the front side of the assembly.
Take off all that stuff, and then you come to the center hose mounts. Here you will see a very "tricky" fastener that I've never seen before - no slot head, no hex head or Torx, just a flat pin! There is one on each side. Pry that pin up with a small flat-head screwdriver, be sure not to lose it. Once out, there is a grommet-looking round thing you have also pry out.
Once you have those items out, you can pull the hose keeper forward and finagle the hoses out of it and remove the keeper. Now you can see the back bolt for the engine cover and remove it to finally see the O2 sensor connectors and wires. Oh, and using a O2 sensor remover (22MM) works great, just be sure that the ear for the 1/4" socket extender is closer to you. Replacing the sensors is very easy, then put everything back.
Oh, I forgot, there are rubber pieces that just sit on other side of the filter assembly that just hold themselves in. Just remember which way they go.
I know this description probably seems very complicated, but I promise, once you start into it is very, very simple! If you are even considering doing your own 02 change, you'll have absolutely no trouble.
I hope it helps.
07-18-2014, 04:26 PM
#3
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I got a code for Bank 1 Sensor 1 02 sensor.
Thoughts? Sadly, I thought that would help very slight stuttering when going up a hill at speed, but it didn't. The stuttering almost seems like you are running over a slightly rough road, but I'm confident something is a bit amiss. The car runs very well otherwise, and this seems to happen mostly on one long hill when I have a business run to Philadelphia!
Thoughts? Sadly, I thought that would help very slight stuttering when going up a hill at speed, but it didn't. The stuttering almost seems like you are running over a slightly rough road, but I'm confident something is a bit amiss. The car runs very well otherwise, and this seems to happen mostly on one long hill when I have a business run to Philadelphia!
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