Hi guys,
So I have been away for a long while. And now I need your help.

I bought my 2001 Maxima brand new and never really had any problems until now well some time in the begning I had to take it into Nissan under waranty fr O2 sensors or something.

Anway...

Car now has 96,000 miles. All Stock.
SES light came on took it to autozone --> P0420.

I searched and read a bunch of threads. I don't know what to do... Should I take it to Nissan and have it re-programmed or try to change the O2 sensor or simulator?

I have no idea what an 02 sensor even looks like and where it is. The only work I have done on the car is change my own oil

Really need your help guys please. Thank you.

 

try to change it yourself; unplug it, then unscrew it from the exhaust (the hard part)

i have not done a sim-mod so i cant comment on that

if you dont have this FSM here: http://forums.maxima.org/general-max...niti-fsms.html

open the "fwd.pdf" then navigate to "Engine Control System - EC" section, P0420

 

P0420/P0430 are result of fouled O2 resulting from faulty coils (I can speak about 2000 maximas).

On 01 max, the coil issue was resolved. I would put all new O2 since you are overdue they last atmost 80K. (they will not throw a code but get lazy resulting in bad MPG).

Don't even think in the direction of pre-cats/cats etc. They are designed for the life of the car in most cases, I have been in the last few yrs having to go to smog checks, the cats definetly are working since I pass smogs in CA in flying colors.

Hence change the O2s and you will not get these non-sense codes, FYI, P0420/P0430 is the most bizzare code with the manufactures mapping all complicated emission into these 2 codes making almost impossible to root cause the problem (I guess this is a way to make money on coils, cats/pre-cats, O2 etc).

I got my O2 from www.ngk.com

Replace them urself and I bet the code will go away, P0420 happened to me at 80K (thx to the coils) and replaced all 4 sensors and till date with 168K, I haven't got those codes back.

 

I too have an 01 purchased new, mine has 25k miles. While under warranty the idiot lights came on (at highway speed). Dealer replaced oxy sensor. Same thing happened a few months later, same fix. I suspect the Nissan supplier had a problem. You can fix this yourself - suggest to look at both OEM and aftermarket types.

 

I am having the same problem with a 0430. Used non-fouler method to pass emissions several weeks ago and light went off. Now it has come back on without foulers. I was thinking it was the cat and not just sensors since my mpg is about 25mpg (premium) when 1-2 years ago it was near 29 (5mt). Do you think the o2 sensor or the coils could cause a slight decrease in power and mpg?

 

I am confused. Did you put the anti-fouler for emission and then took it out again? Why not leave it there?

If you want to change the sensor, make sure you change the front one and get the Denso OEM replacement with factor connectors. Do not buy Bosch and don't crimp wires. This is assuming you have decided to spend money on *a* sensor.

If you want to get the performance back, start with simple stuff like strong fuel system cleaner, MAF cleaner, new air cleaner element. All of three things will run you under $25 combined. If you have done all that, then you can try new MAF and/or new front O2 sensors.

- Vikas

 

I can put it back on, I thought it as a temp fix to pass inspection. I have a fairly new MAF sensor, about 8K miles, but I will try all cleaning things lists. If that doesn't work, then prob O2s will be next. Both fronts should be replaced together, right?

 

I had the same exact problem as you. I bought an o2 simulator from the group deal section and I hooked it up using the directions found here on the org. It worked perfectly and my light turned off. I passed motor vehicle inspection because of it and saved myself the cost and effort of buying new parts and replacing old ones.

 

Almost in all cases, to get rid of P0420 or P0430 you need to replace appropriate pre-cat. But there is no reason to consider your fix to be a temp. It has no side effects. Consider it to be permanent fix.

- Vikas

 

Unfortunately I didn't record the code when this happened to me years ago to my 00 maxima, but 420 sounds familiar. I think it means the car runs lean, plus it would run hot at times.

The coils have a reputation for going bad in 00's.. The dealer wanted 600 for parts, and 250 for labor. Thanks to maxima.org I found changing the coil is easier than changing a spark plug (and spark plug changes are in your owners manual - the dealer suggested they change the plugs too for $125 in labor).

So when you pull the wire off the spark plug, you are half way down removing the coil, you just need to put a flat head screwdriver in the slot next to the arrow symbol on the other end of the coil. This may not make sense while reading it, but go and look at your car and owners manual and it should make sense.

I called other dealers for part prices, and found one that would sell the coils for $350.

So I saved $250 on the coils, and $250 in labor to replace coils. I also bought spark plugs and saved $150 in labor there.

The total time in garage was about 45 minutes. The dealer would have made $400 (and finished in 30 minutes because I go slow/not a mechanic).

I am not saying it is your coils, but there is a good chance. The MAF is also problem, when this started to go bad the car would ping. I had a mechanic fix it for $350, but could have easily done it myself for $150.

 

Okay guys I know it has been a while. I got extremely busy and didn't have time to adress the issue.

The car runs just fine but the CEL is still on. I finally want to fix it.

Firstly, As suggested a good idea is to change the O2 sensors first to see if that will fix the issue?

How simple is it to do? I do my own oil changes and installed HIDs, that's about it. Is there an idiots guide to this?

Also, I want to use OEM parts because I want to be able to drive the car for another 100,000 miles is DaveB still the cheapest source for OEM parts including the sensors?

Lastly, how many will I need?

 

not hard at all. I am another selfmade tech I rented the tool from autozone for $25 and replaced my O2's in about an hour. "took my time and probably did one too many double checks" Check carquest for OEM or get the bosch from autozone for $109. to $119. my old O2's had the same serial number as the Bosch replacements. If it is not a cali emission all you need is 3.

 

Here's a working link for the FSM's ... I may suggest that you download all the .pdf files and burn them to disk ... you never know any more how long the sites remain available
http://www.nicoclub.com/FSM/maxima/

 

Thank you for the manual, although it's probably too much info right now but good to have...

I am going to need a special tool? Which tool would I need to rent?

Didn't realize they are so pricey. So my 01 Max (Bought New in NY) needs 3 of these things?

 

By the way, about 20,000 miles ago I had a problem with my muffler. I took it to a muffler shop and they said something about a heat shield and I think they took it off and welded something together and I didn't need to change the muffler.

Could this be contributing at all? Maybe increasing the heat somehow?

Anyway, you guys seem to think O2 sensors, but spark plugs dont have anything to do with it? I haven't changed mine as of yet.

 

Listen to this man and stop worrying about the O2 sensors. Either replace the pre-cat or run non-foulers or O2 sims.

 

ive been getting the code for years...but i ignore it...because its bad precats...my engine burns oil

 

3000 miles since P0430 code and replaced O2 sensors and no CEL. Just going off what I read versus what I actually did!! All good ideas just choose the route that works for you. Can you still pass inspection with non-foulers???? It is probably cheaper to replace O2's than to replace pre cat. Even with a new pre cat; you still need new O2's if they are old. Why not start with O2's??