We replaced the O2 sensor (bank 2 sensor 2), cleared the codes (O2 and Evap) and the check engine light has been gone for 2 days. Went for emission test today and was rejected, we didn't fail. Emission Tech said to see a mechanic and have them reset it again. Does it take a while for the codes to be over written? How many days do you need to wait before being tested?

Thanks

FWIW, I took an F-150 to AutoZone and asked them to read my codes.. As the guy was showing me I asked him which button i need to avoid pressing to keep from clearing them.. He showed me and I asked "so if I accidentally press this button they'll be erased?".. He said "yep"... So I pressed it and said "Oopsy." :D

He kinda freaked out then I told him "Hey look, that's MY fault NOT yours. Don't worry about it, it's between you and me and you just helped me out a ton." And off I went with no more codes. :D

The OBDII systems on our cars require a specific drive cycle to be completed before it will show "clean". The assumption is that this drive cycle will cause whatever fault caused the light to come on in the first place to come on if there really is a problem. I found this out on my Nissan Maxima; the light came on, and it showed a bad cat. I borrowed a friend's code reader that also had the ability to reset the codes. I reset it after reading the code, but the system still showed a fault (even though the light was out) which would preclude passing a smog check. I was able to find the drive cycle for the Maxima on-line; I'll bet scr38 has the drive cycle for our trucks, but it involved a series of acceleration, coasting, steady state driving, turning off the engine, re-starting, etc. I did that, and got the car to pass smog. Two days later, the light was back on, and it's still on.

Keith

It's like 20-40 key cycles.

Welcome to the club whambino!

I got nothing, but it seems like you have a few god responses already!

As Keith said, certain drive cycles, or patterns, will populate the codes.

On my '98 Pathfinder, it was throwing the code for a minor evap leak, and it was due for a smog check. In the state of California, you can pass a smog check while having up two 2 codes being "incomplete" (Not populated)

I reset my codes then drove around under different driving conditions for about 2 days, which was enough to populate all but 2 monitors - one of them being the evap system.

Pass.

If you didn't fail, they should have told you the exact reason they were not giving you the smog cert.

Thanks everyone, we are going to attempt to pass today. Maybe we didn't drive it long enough. There is no check engine light on (3 days now). We will drive it a while this AM and then head over to the smog check station. We love this Armada, after the dealer finally fixed all the brake problems it's been great. The only other problem that just started is the fuel gauge showing 1/4 and being empty and running out of gas. Nissan won't cover it because it's a 2004, and has 126000 miles. I also found out that I missed 2 recalls and now Nissan won't cover them either. Nissan needs to remember that my next purchase can be elsewhere. I do like the Titan, but I can also purchase a Tundra for my next truck for myself.

If a vehicle is issued a recall I believe that they MUST perform the service. I don't believe they can refuse it. I would look further into that. Have another dealer run the VIN and check for missed recalls and have them take care of it.

We finally passed - went in the AM still failed but only 1 item still not right. Tech said to drive it and come back before they closed. We passed after putting some highway miles of driving between 55-60 mph. About the recalls, I'm going to call Nissan directly this week.
Thanks everyone.