Should I replace my O2's?
 

I'm doing headers in a few weeks and I'm not sure what to do. I was gonna get the rear O2's from a C5 but I'm thinking to myself there isn't anything wrong with the ones I have now. I "know" it's the easiet time to do it now but if it's not broke don't fix it right? The car is getting around 19mpg now(mixed city/highway, mainly city driving) which isn't bad for an A4. I figure if there was any carbon on them I could just clean them off.

I know this is taking the cheaper way but they seem to be working fine. What do you think?

Also, I'm deleting the rear ones when the headers go on.

Should I use the fronts or the rears? Will I need O2 extensions if I use there rears? If so(regardless if I use the fronts or rears) what size wire extensions should I get?

Thanks!

If they work then keep them. Keep the fronts where they are at. Doesn't matter what you do with the as long as the front ones are plugged in. You will throw codes for the rear O2 unless you use O2 sims or have the codes deleted.

I used 2 24" extensions (square connector) and zip tied the excess away from the headers. I drilled a hole in the heat shielding on the driver's side to zip tie to.

The codes will be deleted shortly after if I need a tune after the install.

Thanks :)

I went ahead and got the c5 o2's when I put my headers on. I figure why buy extensions for o2's that'll eventually die when they'll be replaced by c5 o2's anyway.

Yeah, true...but they aren't cheap :lol:

Sensors that work "OK" in the stock hot position may
well not work when you put them out in the cold.
With 5 years and maybe 30K+ miles on them, it's not
a very good bet. Subtract the cost of extensions from
the sensor pair and maybe you'll feel better about doing
the right thing at the right time.

Drifting to a jacked trim and putting new sensors into
that, is just going to put more crust on the new ones.

Yeah don't put the new 02's in with crappy fuel trims. Do it after you get the tune. Or the day before. You don't want to ruin them by running really rich.

Hmmmmm, never thought about that. Thanks!!!!

Also, don't buy the oh so popular Bosch #13111. I put them on when my O2's finally went out. When I had the car retuned at LS1 speed they took them off and put GM O2's on, saying the fuel trims were all over the place with the bosch units. Some on the board said they don't doubt that at all.....

I'll take that into consideration as well.

Thanks!

I would replace the front O2's while you are there and either delete the rears or get O2 sims.

Well the rears will be deleted when I get my tune(shortly after the headers go on).