replacing O2's

[jdlmkviii]

Well my car is roughly 9 years old and I think it's probably gettin around time to replace all the O2 sensors. But does anyone know where they all are and how many there are on a MKVIII? Only one I know about is the one on the throttle body tube...

:feedback:

 

[CaptainZilog]

There are 4. Two pre cat and two post cat. Look on your exhaust pipe and you'll see them. Best way to get them out is to run your car for a little bit to get the pipes warm, then use a sensor socket or an open ended wrench. I don't recommend wd40 as it contaminates the sensor (just as a precaution, if you use it, make sure it's all clean when you put the new ones in.) Also, use some antisieze on the new ones so they are not hard to remove next time.

 

[viol8or]

There are 4. Two pre cat and two post cat

If you have a 95 Mark, you will only have 2 O2 sensors. Pre-cat on both sides. The passenger side can be removed by lowering the exhaust. The driver's side probably isn't doable. I couldn't touch the plug, so I went with the professional. The mechanic charged me $50 to do the install, using my purchased sensor.

If you live in the north hills and want the mechanics location, I'll provide it.

Take care

 

[MonsterMark]

If you have a 95 Mark, you will only have 2 O2 sensors. Pre-cat on both sides. The passenger side can be removed by lowering the exhaust. The driver's side probably isn't doable. I couldn't touch the plug, so I went with the professional. The mechanic charged me $50 to do the install, using my purchased sensor.

Agreed. 2 sensors. Might I add, try to buy them wholesale and then have someone else bust their knuckles. I did them twice and for $50.00, I'd go without beer for a week. LOL. Passenger side is actually fairly easy and doesn't require dropping the exhaust, especially since the flange bolts are I am sure rusted on and you will be cutting them off with a torch. The driver's side is another story. Very tight in there. I have heard some guys cutting off the wires to get a socket over it. There is also a special wrench made to do the trick.

For me, buy some beer and watch someone else do it. But don't get me wrong, if you like to work on your ride, it is a DIY project with lots of patience.

 

[CaptainZilog]

Ah damn, I forgot they didn't switch to OBD-II until 96. My 94 Cougar was OBD-II. Sorry