Replacing oxygen sensors on the AHA (98 A4 V6 30V)
08-31-2008, 01:55 AM
#1
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Replacing oxygen sensors on the AHA (98 A4 V6 30V)
I read the informal tech. article at the link below. I'm sorry, but the task of changing oxygen sensors is not nearly as simple or straightforward as the author leads you to believe. However, let's set that issue aside for the time being.
I spent all night trying to do this, unsuccessfully too. After getting the O2 sensor's wiring loose from the strappings, and removing all the electrical connector panels on the firewall to make space, the O2 sensor is still quite a challenge to remove. On the passenger side (bank 1), the combination valve also is restricting access to the O2 sensor. How the hell I can et a new one in without the scratching the element on wires and metal trying to install it?
Also, the O2 sensors are mounted on the exhaust pipe in an angle facing the fire wall! The only way I can think to try this again is with a 5" extension bar, 4" might be too short, 6" is definitely too long. These things need to be tightened in at 50-55 Nm torque, so there needs to be way to rachet them in and out!
Finally, I could not figure how to access the oxygen sensors from under the car as an alternative... there is a metal panel on the bottom of the car blocking access, and anyway, the O2 sensors are on the top of the exhaust pipe about half way up the height of the hood equipment. I find it hard to imagine the O2 sensors could be changed from under the car without first removing the exhaust section they are in before the catalytic converter.
If anyone has any tips or advice on how to do this procedure better, definitely would appreciate the help!<ul><li><a href="https://forums.audiworld.com/a4/msgs/1894039.phtml">Replacing oxygen sensors on the V6 30v</a></li></ul>
I spent all night trying to do this, unsuccessfully too. After getting the O2 sensor's wiring loose from the strappings, and removing all the electrical connector panels on the firewall to make space, the O2 sensor is still quite a challenge to remove. On the passenger side (bank 1), the combination valve also is restricting access to the O2 sensor. How the hell I can et a new one in without the scratching the element on wires and metal trying to install it?
Also, the O2 sensors are mounted on the exhaust pipe in an angle facing the fire wall! The only way I can think to try this again is with a 5" extension bar, 4" might be too short, 6" is definitely too long. These things need to be tightened in at 50-55 Nm torque, so there needs to be way to rachet them in and out!
Finally, I could not figure how to access the oxygen sensors from under the car as an alternative... there is a metal panel on the bottom of the car blocking access, and anyway, the O2 sensors are on the top of the exhaust pipe about half way up the height of the hood equipment. I find it hard to imagine the O2 sensors could be changed from under the car without first removing the exhaust section they are in before the catalytic converter.
If anyone has any tips or advice on how to do this procedure better, definitely would appreciate the help!<ul><li><a href="https://forums.audiworld.com/a4/msgs/1894039.phtml">Replacing oxygen sensors on the V6 30v</a></li></ul>
08-31-2008, 04:46 AM
#3
removing from underneath is easier imo
having access to a lift helps. Not sure what you mean by metal panel, the heat shield can easily be snapped out of the way. But it is possible to remove them from the top, as always the right tools make all the difference.
08-31-2008, 07:48 AM
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I really don't think so
I pulled the tire and followed the exhaust pipe with my hand to the O2 sensor. So, this message comes from "hands on" investigation.
On this car (98 A4 Quattro V6 30V), the O2 sensor is on the exhaust pipe almost exactly above the axle and behind the strut, about half way up from the bottom. Bentley conveniently lacks a section for installing and removing O2 sensors on this car too.
Accessing the sensor from the wheel well doesn't work, as the section behind the strut and above the axle seems to be non-removeable metal. Only along the sides is there a panel that come off, and the O2 sensor is clearly inaccessible with the wheel well cover removed (on the passenger side at least, the most difficult location).
From the bottom it also seems impossible, because the axle and the bottom of the cylinder heads are in the way. There is so much non-removable equipment in the way, and the thing points up and must be tightened to 50 nm.
From under the hood actually still seems the easiest way to me, and even that is not easy.
Am I missing something here?
On this car (98 A4 Quattro V6 30V), the O2 sensor is on the exhaust pipe almost exactly above the axle and behind the strut, about half way up from the bottom. Bentley conveniently lacks a section for installing and removing O2 sensors on this car too.
Accessing the sensor from the wheel well doesn't work, as the section behind the strut and above the axle seems to be non-removeable metal. Only along the sides is there a panel that come off, and the O2 sensor is clearly inaccessible with the wheel well cover removed (on the passenger side at least, the most difficult location).
From the bottom it also seems impossible, because the axle and the bottom of the cylinder heads are in the way. There is so much non-removable equipment in the way, and the thing points up and must be tightened to 50 nm.
From under the hood actually still seems the easiest way to me, and even that is not easy.
Am I missing something here?
08-31-2008, 07:58 AM
#7
meh, I've done it several times from underneath, it's not that hard
<center><img src="http://tomasz.data2net.org/gallery-albums/album97/Passat_003_Large.sized.jpg"></center><p>
put it on a lift so you can really reach in there, if you're laying on the ground you won't have much freedom of movement. Correct length swivel extensions are a must have, otherwise it's pretty straight foreward.
put it on a lift so you can really reach in there, if you're laying on the ground you won't have much freedom of movement. Correct length swivel extensions are a must have, otherwise it's pretty straight foreward.
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08-31-2008, 08:16 AM
#8
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Ok, I can see hand screwing it in and out from under with the tire removed
That's probably how I will do this. Much safer handling with the element exposed.
But loosening and tightening with a torque wrench from under the car? That must be done under the hood with an extension I'd say. You'd need a U-swivel extension to do it all underneath, and I don't think they make such a thing, do they? That's the part I just can't follow, sorry.
But loosening and tightening with a torque wrench from under the car? That must be done under the hood with an extension I'd say. You'd need a U-swivel extension to do it all underneath, and I don't think they make such a thing, do they? That's the part I just can't follow, sorry.
08-31-2008, 11:03 AM
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Got 'em out! They are snow white! (a little bit of gray on the back end)
Does white on the O2 sensor mean carbon deposits like it does on the spark plugs? (which also have grainy white on them)
Could carbon deposits be the reason why my ECU thinks the car is running rich and cuting back fuel (negative trims <-10%)? (i.e. O2 sensor is coated and can't see O2 in the exhaust) Or, is this just indicative of another problem (past or present) that is causing me to actually run rich?
Could carbon deposits be the reason why my ECU thinks the car is running rich and cuting back fuel (negative trims <-10%)? (i.e. O2 sensor is coated and can't see O2 in the exhaust) Or, is this just indicative of another problem (past or present) that is causing me to actually run rich?