o2 sensor spacers/defoulers

[98 a4 1.8]

I have a testpipe installed and got a CEL when I put it in, I know that when a testpipe is installed you also need to put a spacer when putting the o2 sensors back in. The problem is that I've heard mixed opinions that only the secondary o2 sensor needs the spacer, is this true or do both sensors need the spacer. Thanks

[bigblue]

the secondary is after the actual catalyst... so yes just the rear.

[SykoraA4]

yep second 02 sensor. you'll need one of these:
http://www.raimotorsport.com/RAI-J-P...p/11620vib.htm

[98 a4 1.8]

Ok thanks for the info, I was thinking of getting this one or the one that you suggested
http://www.europaparts.com/034motors...or-spacer.html

[holywar0902]

I have used to RAI spacer as well as another spacer some guy was making and selling and neither worked for me. My cel still comes on a lot, it will go off for a day or 2 and come back on with the same code of course. I did do some searching a while back and some say the spacers will work on non drive by wire cars, but its a toss up on drive by wire cars. Just food for thought