Jacob42

I'm relatively new to the forum and I've been reading around a lot but I have a few questions.
So I'm planning on dropping my transmission pan and cleaning it all out but is there any additional maintenance / cleaning things I should do while it's open?
I replaced the alternator and battery as well but the first alternator didn't fit properly and rattled but it worked fine, the company I purchased it from (AM auto parts) sent a replacement and it fit but immediately after installing it the battery and brake lights came on and won't go off. I had AutoZone check the charging system and it was working correctly. Battery voltage is above 14V while running. I've been driving it for a few weeks without problems. Does anyone know what could cause this?
And finally I'm trying to get emissions done but there's a bank 2 sensor 2 problem, it constantly reads 0.300V it will occasionally go to 0.310v. It tripped a p0160 code. Do you think the sensor is bad? The cat on that bank is also bad but I've been able to pass inspection every year by adding BG 44K fuel cleaner. I reset the codes and it hasn't come back yet but the readings are the same so I imagine it's only a matter of time.

maxiiiboy

You are asking for help, but you have not even bothered to tell us what the MY of your car is ..... this makes it hard for anybody to help you.
Yes, you could "do things while it's open", but why would you? Are you experiencing any problems such as delayed or rough shifting ??
If the (battery voltage is indeed at least 14.2 V with the engine running) AND (you measured it on the battery itself, not on the connector), the alternator is charging the battery. If, in spite of that, the lights are on, you need to investigate the logic controlling these lights, and go from there.
Well, if the Bank 2 cat is bad (as you just said), then the associated sensor (B2 S2) is only doing its job by reporting that the B2 cat is bad. Am I missing something?

Jacob42

Sorry, I totally forgot. Its a 2001 Nissan Maxima
It's a little rough shifting from 1st to 2nd, but I was mostly asking about additional preventative maintenance.
How exactly would I go about investigating the logic?
Wouldn't the readings still fluctuate from high to low? With the cat at reduced efficiency shouldn't the b2 s2 have readings closer to the b2 s1? Right now it's staying at a constant 0.3V even while the engine is off. The other sensors go to 0.0V when the engine is off. Or does the b2 s2 operate differently?
Thanks!

maxiiiboy

Re. your AT: Drop the pan and clean the magnets. I would not bother removing and cleaning the screen "filter"; it's usually clean unless the car was greatly abused. After you put things back together, do two more consecutive drain&fills, with a bit of driving in-between. That should replace 90+% of your transmission fluid. Your shifting should be smoother. If not, I would consider installing a grounding kit before trying any other measures.

Re. your BAT and BRK light: When these lights are on, it's normally an indication that the battery is not being charged. However, you claim that with the engine running, the voltage on the battery is 14+V. That's a contradiction, unless: a) You did not measure voltage on the battery, but voltage on one of the connecting leads; OR b) There is something wrong with the lights and/or the logic controlling them.
Make sure your all the relevant contacts are clean! If the problem persists, read the SC section of the FSM. You can download it from here: http://boredmder.com/FSMs/Nissan/Maxima/ .

Re. your O2 sensor: The front and rear sensor perform very different functions. The Front sensor is used to monitor the fuel trim; the voltage on it should constantly oscillate, as the ECU is trying to maintain the ideal trim. The only purpose of the Rear sensor to monitor the efficiency of your pre-Cat. If your pre-Cat works well, the voltage should be level/stable. See the EC section of the FSM for details, including diagnostic produres.