does bad knock sensor fail me for smog on 99 pathfinder?

[albsolo1]

if i get a bad knock sensor code on OBD II will i fail smog? i also get a bad O2 sensor which i know will fail me but the repair guys all want around 300- 500 just for the knock sensor.... anybody help, please.

[fueler]

Yes, here in CA you will fail emissions testing if you have any check engine light. You would have to make a repair of some sort. You can probably do an O2 simuilator for $40 http://supersoda.com/detail.php?id=00000000079 a knock sensor tho, there is no substitute. after a repair, or simulator, you will have to reset your battery/ECU, and then drive at least 40 miles for your ECU to run all the diagnostics or it will still fail smog. Go to a place that does free re-test just in case.

[Acey]

cracked manifolds caused a o2 sensor to go out on me. It also falsely tripped the knock sensor code too.

[albsolo1]

cracked manifold.... hmm, and i was hopin not to take off the manifold to get to the knock sensor... know how to check if the manifold is cracked or is that just a visual inspection?

[Acey]

First, my pathy is a 96 with a well known exhaust manifold cracking issue. I don't know if the manifold issue would affect you with your 99. I bought it knowing one was cracked as I could hear it when starting when it was cold. It sounds like a a nasty tick/knock when cold that lessened as it heats up. The crack shrinks due to metal expansion. It should be constant sound though unlike the ticking lifter. I barely caught the tail end of the extended manifold warranty from nissan. One manifold was cracked all the way through and the other had a crack. I didn't expect that as it didn't sound THAT bad. My red O2 sensor codde was up and I also had the code for the knock sensor. I had the codes reset before the work and they came up with the o2 and knock sensor twice. The manifolds were replaced but they wouldn't cover the O2 under warranty so bought it and I did that myself separately. After everything was done, I had the code reset and haven't heard from that knock sensor since. That was 43k miles ago. If you don't know what a cracked exhaust manifold sounds like, try to find a friend or mechanic that recognizes that sound as it is pretty distinct. It sounds more like a knock sound which is why I could see it tripping the knock sensor. It did sound like a pinging sound like if you have ever ran bad gas before.