Both fwd O2 sensors?
 

Both went bad within a week of each other. I took the Z down to the dealer and they diagnosed that both O2 sensors in the front were bad so I'm wondering if that has something to do with my Berk HFCS (they have been on trouble free over a year) or maybe my exhaust, or if I'm just unlucky?

Also should I just let dealer put them on for 700 bucks or DIY for 400 bucks in parts from NAPA!

Hopefully that's a fluke thing. I've got the same exhaust setup and it's been about a year and a half now, but no issues (yet).

I think it'd be a pretty simple DIY, no? May be a little tight is all.

Both fwd O2 sensors?
 

I can put her up on jack stands. I'll watch some DIY vids tonight to decide.

Are you throwing a code? If so what is it?

When you say front, are you talking about the very front O2's or the ones behind the cats?

The fronts wouldn't be effected by the cats because 1. They're in front of them, and 2. Running hfc's makes you run leaner and not richer. It's not like you where dumping raw fuel on them and fouling them out.

Now if you're talking about the rear O2's, you're still leaner than OEM but you could be flowing more fumes by them in volume even though its leaner fumes resulting in an early foul. But good news is 1. Just buy any O2 from napa and cut and splice the wires into the correct spots (way cheaper!) as long as its a 4 wire O2 and design/thread pitch etc. or 2. Just get a tune and turn them off because you don't need them. The rears are just there to tell you your cats ****** up.

Both fwd O2 sensors?
 

Fronts as in just in front of cats. And after sensor swap the codes came back. Soooooo....

?

The dealership guys replaced my old (functional) sensors and are now looking to get my car in for a whole day to troubleshoot.

Maybe it's my tune.

Oh well at least it's not 700 dollars worth of sensors.

Why dealer it then? If you have a tune then the tuner should be the one to diagnose it. A dealer isn't going to be able to go in like uprev.

Yeah. I thought they would be able to run it down. Also check to make sure sensors were operating properly. I think ill head to the tuner to complete the diagnosis.

p2a03.

I run a Ready Link OBDII all the time so clearing is easy even on the fly. I just want to make sure my fuel mix is safe for the cats. (ie sensors are working properly)

Hope it works out with a re tune. I remember you switching modes via steering wheel..does it happen in every mode (tune)? Just purchase a supercharger too!!

WOW! I have been throwing the same code for over a year now and I'm still trying to figure it out. I had a buddy check up on that code and apparently in some cases a small exhaust leak can cause it.

I'll be tightening down my exhaust here this week and clearing the code to see if it helps.

But yeah, I went to bring my car to the dealer thinking it was just a bad o2 sensor but the tech blamed it on my HFC because of the anti fouler bung....:shakes head:
He said the rear sensors were throwing off the front. Uhhhh, I don't think so Mr.'Certified' Nissan Tech or their 'top' tech as they called him. I was lucky enough to have a nice service guy because he waived my $85 inspection fee because he knew it was a bulls*** diagnosis.

I was actually going to post up on here soon if tightening the exhaust didn't work to see if anyone knew the problem.

Denso part number: 234-9071
NGK part number: 25685

Every tune map. I'm going to stop by tuner to ask them what they think (MAC auto sport). It's really no big deal, as I just clear it via a OBD2 iPhone app. (I can do it on the fly)

As for the Supercharger... Hell yeah! I'm working on it. (putting together some funds):tup:

Thanks Andrew. I'm pretty sure it is not the sensors.