mk4 VR6 12v Pre Cat O2

[MarcusCoyle]

i swapped out my pre cat 02 sensor today to get rid of a plaging CEL, get some PB Blaster penetrating lube, and an adjustable wrench and you'll be in pretty good shape.. under the passenger side of the car there is a small box with one loomed wire going into it and two rubber cuated wires coming out of it, the box is just a cover and is held on with 2 10mm nuts, when you take them off the box will come loose, flip it over and there are 2 plugs, one is to your pre-cat(bigger) and one is to your post cat, the post cat really dosnt do anything, just pretty much makes sure your cat is working... anyway i was doing this as i was changing my oil, so i sprayed the bolt end of the existing sensor with pb blaster every 5 minutes for about 20 minutes, and followed each spray with a few ferm hits to the sensor with the edjustable wrench i was going to use, i have a jetta and its in a really akward place maybe on golf it wont be. its a PITA to get the wrench on there but you will, i put a little force into mine and it came off really easily, you probably wont get it out without using a penetrating lube.. you have to re-route the wire and put a heat shield on the new wire, but its quick and easy ( i got sand in my eyes doing it, so keep that in mind when your messing with the heat shield) if you go to the mk4 section of vwforum.com they is a DIY with pictures, but he had an o2 sensor tool.


i got the sensor from www.autopartswarehouse.com (http://www.autopartswarehouse.com) for $40.25, the can of PB blaster cost a little under 3 bucks.. so unless your under warrenty you should pretty much do it yourself - its cake

[JASONBALL]

I gave you reps for a good post

[Decker1.8t]

What code was the CEL throwing. I thought it was the POSt cat sensor that throws the annoying CEL. It's usually defeated by putting a spacer (spark plug arrestor that's been drilled out) on the o2 sensor.

good post though. whatever works for you.