Changed Front Oxygen Sensors on a 1997 A6
07-24-2006, 06:27 PM
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Changed Front Oxygen Sensors on a 1997 A6
Just did my front oxygen sensors this weekend. I used Bosch OEM replacements that have the wires and connectors.
After reading the posts on the forum about this job, I want to comment that in my view the job is a pain in the ***.
Getting the old sensors out :
The passenger side is not bad. There is enough room to get a breaker bar in the engine compartment and break the old sensor free. The single black connection is "hidden" behind the row of electrical connectors that the two white wires plug into. The driver side is too tight to get any "capable breaker bar" on the sensor. Approaching the sensor from the bottom side (under the car) might have been easier than approaching the sensor from the top. To make things easier I removed the air intake sound damper on the back of the engine which gave me more room to work (on the sensor and connector) and also allowed another "angle of attack" to get at the sensor. Then I was able to get a breaker bar in and get about 1 inch of travel at the top of the handle, enough to get the sensor "popped free". I have both a claw foot and socket for O2 sensors and full sets of 3/8" and 1/2 " socket sets. The sensors did come out very easily after I got the first ? turn or so on the sensor.
Replacing the old harness (wires):
The old harnesses were both very tightly tie-wrapped to the back engine coolant tube. Getting the tie-wraps "cut by feel" was a pain. I tie-wrapped the new harnesses in different places. Removing the harnesses from the metal clips mounted to the engine was not difficult at all. Replacing the connectors was a little surprise. You replace the bottom half of the connector that is mounted in a piece of metal attached to the firewall. Just pull the top half off and "tug and jerk" aggressively on the bottom half. The signal (black wire) was mounted in a couple of circular clips and were easy to remove and replace. The passenger side signal wire (black) was located behind the bank of electrical connectors and a little difficult to spot.
Vacuum Lines :
Since I had the air intake sound damper off I replaced some ratty looking vacuum lines. Several just tore apart when I removed them and the cloth shell was just disintegrating.
Installing new sensors :
About the best thing to happen here was the new sensors were pre-coated with a gray colored antiseize compound. The passenger side O2 sensor was pretty easy since a torque wrench would fit in the available space. For the driver side I just got the sensor as tight as I could with a 3/8" drive. I could get my torque wrench on the sensor but there was not enough room to make the wrench work, i.e. the handle of the wrench could only move an inch or so and would not "ratchet". I tried various combinations of the O2 socket, claw foot, ratchets drives, universals, etc., but just could not get enough "Swing room" to make the torque wrench work. As a test after I torqued the passenger side with a torque wrench I tried to tighten it more with the 3/8" drive I used on the driver side. I couldn't tighten the sensor anymore..I hope the driver side is tight enough, it probably is. My sensors came with thin crush washers (the kind of washer on a spark plug). I have read some posts that mention copper washers. Personally I think a crush washer is better for this application. The old sensors also had crush washers.
Resetting the ECU : Again another pain in the ***. Pull the bottom of the back seat, pull the negative battery terminal, put it all back together and reset the radio "SAFE" mode.
From start to finish it the job took about five hours including a trip to get some vacuum hose, a few breaks, 45 minute test drive, etc. I do tend to be slow, methodical and happy with the outcome of my work.
As far as things to make the job faster :
Just cut the wires right away. I know it is a little risky but it will make the job go faster. Being cautious I made sure I could get the sensors out (by loosening them) before I cut the wires. That did make things go a little slower.
Soldering in a new sensor or doing a good crimp job might be easier than replacing the harness. Again the passenger side wasn't too bad for harness replacement and actually after I pulled the air intake sound damper the driver side harness replacement wasn't too bad either. Both sides did have the pain in the *** tie-wraps on the rear engine coolant tube.
In summary I'm really not trying to discourage anyone from doing the job. It isn't too hard but it is a pain in the *** at times. In some ways I would rather do a timing belt, at least I have plenty of room to work.
After reading the posts on the forum about this job, I want to comment that in my view the job is a pain in the ***.
Getting the old sensors out :
The passenger side is not bad. There is enough room to get a breaker bar in the engine compartment and break the old sensor free. The single black connection is "hidden" behind the row of electrical connectors that the two white wires plug into. The driver side is too tight to get any "capable breaker bar" on the sensor. Approaching the sensor from the bottom side (under the car) might have been easier than approaching the sensor from the top. To make things easier I removed the air intake sound damper on the back of the engine which gave me more room to work (on the sensor and connector) and also allowed another "angle of attack" to get at the sensor. Then I was able to get a breaker bar in and get about 1 inch of travel at the top of the handle, enough to get the sensor "popped free". I have both a claw foot and socket for O2 sensors and full sets of 3/8" and 1/2 " socket sets. The sensors did come out very easily after I got the first ? turn or so on the sensor.
Replacing the old harness (wires):
The old harnesses were both very tightly tie-wrapped to the back engine coolant tube. Getting the tie-wraps "cut by feel" was a pain. I tie-wrapped the new harnesses in different places. Removing the harnesses from the metal clips mounted to the engine was not difficult at all. Replacing the connectors was a little surprise. You replace the bottom half of the connector that is mounted in a piece of metal attached to the firewall. Just pull the top half off and "tug and jerk" aggressively on the bottom half. The signal (black wire) was mounted in a couple of circular clips and were easy to remove and replace. The passenger side signal wire (black) was located behind the bank of electrical connectors and a little difficult to spot.
Vacuum Lines :
Since I had the air intake sound damper off I replaced some ratty looking vacuum lines. Several just tore apart when I removed them and the cloth shell was just disintegrating.
Installing new sensors :
About the best thing to happen here was the new sensors were pre-coated with a gray colored antiseize compound. The passenger side O2 sensor was pretty easy since a torque wrench would fit in the available space. For the driver side I just got the sensor as tight as I could with a 3/8" drive. I could get my torque wrench on the sensor but there was not enough room to make the wrench work, i.e. the handle of the wrench could only move an inch or so and would not "ratchet". I tried various combinations of the O2 socket, claw foot, ratchets drives, universals, etc., but just could not get enough "Swing room" to make the torque wrench work. As a test after I torqued the passenger side with a torque wrench I tried to tighten it more with the 3/8" drive I used on the driver side. I couldn't tighten the sensor anymore..I hope the driver side is tight enough, it probably is. My sensors came with thin crush washers (the kind of washer on a spark plug). I have read some posts that mention copper washers. Personally I think a crush washer is better for this application. The old sensors also had crush washers.
Resetting the ECU : Again another pain in the ***. Pull the bottom of the back seat, pull the negative battery terminal, put it all back together and reset the radio "SAFE" mode.
From start to finish it the job took about five hours including a trip to get some vacuum hose, a few breaks, 45 minute test drive, etc. I do tend to be slow, methodical and happy with the outcome of my work.
As far as things to make the job faster :
Just cut the wires right away. I know it is a little risky but it will make the job go faster. Being cautious I made sure I could get the sensors out (by loosening them) before I cut the wires. That did make things go a little slower.
Soldering in a new sensor or doing a good crimp job might be easier than replacing the harness. Again the passenger side wasn't too bad for harness replacement and actually after I pulled the air intake sound damper the driver side harness replacement wasn't too bad either. Both sides did have the pain in the *** tie-wraps on the rear engine coolant tube.
In summary I'm really not trying to discourage anyone from doing the job. It isn't too hard but it is a pain in the *** at times. In some ways I would rather do a timing belt, at least I have plenty of room to work.
07-24-2006, 08:33 PM
#4
if that was a PITA wait until you replace the power steering rack....hope u never have to
no, seriosly those things you mentioned were pieces of cake
resseting the ECU was hard for you? puting the SAFE code into the radio was a PITA? come on!!!
resseting the ECU was hard for you? puting the SAFE code into the radio was a PITA? come on!!!
07-25-2006, 06:58 AM
#6
I ended up having to cut the wires and break off the top of the old sensor to get a...
regular socket to fit on there to give me enough leverage to break it loose. The O2 sensor socket tore the wires when I used it. Kinda' worthless!
07-25-2006, 10:25 PM
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Well the main reason I made the post is because people say it is "Piece of cake" and I disagree.
Oil changes, fuel filter, spark plugs, cleaning the IAC, air filter. I'd say those are pieces of cake.
Tranny filter, timing belt, water pump are at a different level.
Steering rack, heater core are at another level.
The O2 sensors are in the mix somewhere. Personally, I just don't think the front O2 filters are a piece of cake.
A lot of the posts on the board are about "jobs" are incomplete and misleading. Some are damn near fradulent, ie.e if you ask a question or two you can tell the person never did a particular job but was near the area or obviously did the job incorrectly (that comment isn't directed at you).
Maybe you are a just much better mechanic than I am.
Tranny filter, timing belt, water pump are at a different level.
Steering rack, heater core are at another level.
The O2 sensors are in the mix somewhere. Personally, I just don't think the front O2 filters are a piece of cake.
A lot of the posts on the board are about "jobs" are incomplete and misleading. Some are damn near fradulent, ie.e if you ask a question or two you can tell the person never did a particular job but was near the area or obviously did the job incorrectly (that comment isn't directed at you).
Maybe you are a just much better mechanic than I am.
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10-03-2007, 07:29 PM
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Just did this on my car....
1994 100CS Quattro
It was very easy. I don't know why you would even consider getting under the car, I did once and that was because I dropped my O2 sensor socket. The entire procedure took me just under 1 hour. Most frustrating part to me was getting the rubber boot back over the signal wire, other then that it was very very straightforward.
It was very easy. I don't know why you would even consider getting under the car, I did once and that was because I dropped my O2 sensor socket. The entire procedure took me just under 1 hour. Most frustrating part to me was getting the rubber boot back over the signal wire, other then that it was very very straightforward.
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