I've been having some odd transmission issues with the Maxima the past few days. I blew a transmission cooler line last week and had to top it back off with 2 qts of fluid, which I managed to put the wrong fluid in it, but that has been remedied now. I did a fluid flush yesterday and filled it back up with the proper fluid, but it's still shifting rather odd. It was shifting good and firm, even with the wrong fluid in it. All of a sudden a couple of days ago it started shifting a lot softer and having a harder time downshifting, along with feeling a little sluggish.

It also has been having a hard time when it's cold between 1st and 2nd - it'll slip and feel like it takes a second to go in gear, then once it does it feels like it slams into gear if you're not being gentle. It only does it once though and won't do it again until it sits for a few hours. I've been trying to do some research and see what I need to do about this, because it's obviously not right and I don't think it's something I can diagnose myself. It didn't start acting up until I had the issue with the cooler line.

Tonight I decided to hook my OBD code scanner up to it and it found a P0325 Knock Sensor code, which seems like it could explain some of the symptoms as well.

So at this point i'm still rather confused though. Should I go ahead and take it to a transmission shop, or should I take it to Nissan and let them run Consult on it first? I would hope that the transmission isn't trying to crap out already... it seems more like a valve body or torque converter issue, but some more insight would be greatly appreciated. Thanks guys!

What other code came up with the KS code? The KS will not trip a check engine

Brad - the check engine light didn't come on. I just randomly decided to scan the codes and it had that code stored.

I'm starting to believe there's not a transmission issue anymore. The engine seems to be hesitating at certain times in the higher RPM range, like 4k and above. The transmission seems to be shifting better, but the car seems like it's bogging down more at times

Alright I unhooked the battery last night before going to bed and hooked it back up this morning. Checked the codes again tonight - Still no check engine light, but the P0325 code is showing up twice now.

Replace your KS.....they are like $20 on amazon.

Report back with your findings. The KS could be the result of high RPM hesitation, do you have a miss type feeling when you are at idle?

Also on a side note, I took it through emissions in January and it would not pass if there are any codes present. I'm with Brad on this one. That knock sensor can be replaced in about 20-30 minutes. I changed Brad's out in the AAP parking lot.

Yeah i'm gonna go pick up a knock sensor tonight and put it on. It's missing a little at idle and hesitating/stumbling a little at all RPM's. Hopefully it'll sort out the problems.

New knock sensor and it seems a little better. I put some fuel system cleaner in the tank too and I'm gonna clean the K&N this weekend. Its still not completely back to normal, but its getting there I think.

when you changed the tranny fluid did you change the filter? Hope you didnt.

what kind of spark plugs are in there? Ngk or bust

No filter change, just drain and fill with some Lubeguard Red.

Jeremiah put NGKs in it before he brought it up here.

Well it's back to acting up again today. I've decided i'm just gonna take it to my mechanic next week and let him figure it out. I think it's surpassed my knowledge at this point.