CTMaximaSE

I seen some post’s on this issue & know that this is a common problem, but every car is different.
2000 Nissan Maxima SE auto with about 122k. All stock. Just recently the check engine light came on. So I ran a diagnostic / scan on it and its coming up with the code P0430 Catalytic Efficiency Below Threshold Bank 2. I cleared the code & changed the air filter and was able to drive over 1200 miles & CEL came on again. Reset it again-scanner, was able to drive the car about 500 miles. Light came on. Disconned the battery this time; and went about 150 miles & the light is back on.
All this started happening after I had a new exhaust pipe and muffler put on. Done at Monro. I brought it back to them to check for any exhaust leaks. And they did not find anything wrong or any leaks. Also the cat’s on the car looked fine, they were not hot or red. They wanted to sell me an engine / fuel system cleaning for about $ 150. And they said that could do it. I was not sure about that. I did not have them do it.

Also it seems that the Light comes on when it’s colder & rainy. It always comes on when about 5 to 10 minutes after I start it up.
And, the car starts, runs fine and has full power with the light on.
Some history
New plugs & new coil packs at 95k.

Any thoughts on what’s causing the code to show up ???

Thanks

00Lightsout

1. When the precats loose 5% of efficiency they will throw a P0430/P0420 code.

2. The Precats and Cat run best at normal operating temp...the hotter the better.

3. Usually it's the sign of a failing 02 sensor before a Cat goes bad.

4. The Right Bank(rear) cat is the most expensive cat to replace b/c it's built into the y-pipe.

5. you can get away with trying to run a BG 44K fuel system cleaner...autorized by NISSAN and sold at the dealer or other local shops....MY FAVORITE FUEL SYSTEM RESTORATION & CLEANSER.<<--------START HERE

6. Clear the code 1 more time the moment before you fill it up at the gas station with BG 44K.
-clear code
-drive to station
-pour in BG 44K
-fill with proper amount of fuel following the BG 44K instruction
-Update this thread with results...
-if your code comes back, start with the Right bank post precat 02 sensor(the one
at the bottom of the y-pipe coming from "rear" header precat, and is located at
the "U" switchback for the y-pipe.

OH...are you CA emissions or FED emissions??...from the sound of it you are CA emissions ugh!

BigLou55

iTrader: (6)

I had a same problem last month I could actually hear my cat when I started the car in the morning with the rattle sound....I reset my code about 4 times and after about 300 miles or so it would always come back on so I just said screw it and bought an eastern precat from rockauto.com, the wire mesh and gasket from nissan. Code is gone been roughly 800 miles and no code. The fact that it keeps coming back you may wanna save up for that precat...hopefully you dont live in CA, if not its only about 180. good luck

00Lightsout

even if you do live an CA...some shops don't really care as long as it passes the sniffer test and the 02 are NOT on Simulators!

CTMaximaSE

Update.
Live in CT.
Not sure what type of emissions I have CA or Fed. How can you tell ?
I have 4 - 02 Sensors.

I saw the post on - How to clean MAF under $ 10. So went down to Autozone and purchased the CRC Mass Air Flow Sensor Cleaner can and cleaned the sensor.
The car idles nicer and runs smoother.

Also, I purchased a bottle of CRC Guarnateed To Pass Complete Fuel System Cleaner No 05063. Poured in & disconnected to battery.

I have put over 200 miles on the car and no Light on !!!

I have ordered the BG 44k on ebay. And will using it shortly.

Thanks !!! 00Lightsout for your post And others !!

VQP0WER

The light will come back on. You don't think resetting the computer will make it go away, do you? I'm betting you will have to change out your O2 and precat.

You have a Cali spec max.

00Lightsout

True, it could come back eventually. I'd like to know if we are able to use MAF cleaner to clean an O2 Sensor!

have you ever replaced an O2 sensor on this car before...if not it could be that and not your cat.

99greddymax

iTrader: (7)

I had this code on my nissan frontier.. I wasn't going to spend 5 bills to replace the precat, so I just did the spark plug antifouler trick. Problem solved. Passed smog with flying colors.

killemall2k

this is an ongoing problem for me aswell, ive got an 00 max. i've already replaced one of the o2 sensors but the light only comes on when its muggy/wet similiar to your problem. how sure are you guys that its definitely the precat?

VQP0WER

It has to be the precat, pretty common for the Maxima. I replaced mine before I wrecked. You can get a Eastern Precat for like $150 from RockAuto. You could also gut the OEM precat and get O2 sim, but if you are in a emissions testing state, you will have problems.

knight_yyz

iTrader: (40)

It's an o2 or a cat... Here's a synopsis of an article I found on how your o2's work. Basically the ECU reads the upstream and downstream o2's and compares the voltages. They should be different by X amount. Nissan's ECU determines the voltage of X and throws a code when that value is out...
So your o2 near the exhaust manifold (upstream) reads the emissions and produces a voltage to the ECU based on that reading. Then the emissions goes through the cat converter and is read by the 2nd o2 (downstream) And compares the voltages. If the comparison is wrong there are a few codes that can be thrown by the ECU.
So if the o2 has gone bad and sends a wrong voltage that will cause a code. If the cat has gone bad and is not converting the exhaust properly, that will cause a code.

This can also happen if you are running too lean (mad MAF) If the 1st o2 reads low emissions, (because there is not enough fuel to burn to cause emissions) then there will not be enough of a change for the second o2 to read.

Thorzdad

Just drive it. We've had the code for years and have never had a problem with the car. Our local Nissan shop told us it's just a glitch in the programming and not a failure of either the sensors or the cat. The computer just throws the code, but doesn't do anything else. No performance adjustments. Just throws the code.

02Lightblue maxii

hmmm very weiird

CTMaximaSE

Used the MAF cleaner to clean only the MAF sensor.

Never replaced any O2 sensor's. They have 123k on them now.

dustey

iTrader: (1)

It's the pre-cat, period. It's a super common problem and if you don't mind driving with a SES light on, you can just drive it till the wheels fall off with it on.

I chased that P0430 code for about two years. I replaced everything (was also having a misfiring problem) including plugs (OEM), MAF (OEM), all 4 O2 sensors (OE Direct replacement), air filter (OEM), BK44, etc... you get the idea. I hate driving with the light on so I just replaced the cat with one from Bosal (had gasket issues with the Eastern, btw) for like $200 and it went away. I'd like to think it helps the environment and/or gas mileage, but I kind of doubt it...

L36

iTrader: (4)

Had same issue, just got an eastern cat and the car began running great. On another note, i don't have a cat in the rear bank, just an o2 simulator. The previous owner put it and well no problems with it.

00Lightsout

I've chased it for years too...all four O2's, all coilpacks, all plugs, crank sensor, cam sensor, MAF(constantly cleaning = no change), BG 44k, injen CAI with heat wrap and hydroshield...on and on...I think I just need to get new cats...d**n CA spec crap! My mileage SUCKS!!

00Lightsout

I HATE how a 5% decrease in CAT efficiency causes a CODE...who created that limitation?

cabernet

It doesn't hurt the environment. I have the 0430 code and turned it off with a cheap code reader, drove it 50 miles and passed smog in Calif with flying colors. The emission levels were less than 10% of the passable limits. So obviously this is just a bogus code. And yes, I've had the ECU reprogrammed at the dealer before to account for their worthless sensing system.

dustey

iTrader: (1)

CARB? I would imagine since all 2001's are Cali-spec and California has the strictest emission laws of all states, the computer is designed to throw a code once it is in range of falling out of compliance with the CA laws...

Just my guess, though.

nicknails

I've have a P0430 code for quite a while now and I need it fixed for inspection (NH). I took it to the dealer and they wanted to replace the cat (didn't say which one) and an O2 sensor (Bank 2). My question is this; if an O2 sensor is bad and throws the catalytic efficiency reading off, how do they know the cat needs to be replaced? I hooked up my new scanner and most of the O2's fluctuate between 0 and 1, which is what they're supposed to do. One of the sensors stays a steady 0.29V all the time, it doesn't move at all. Thoughts?

Eirik

iTrader: (2)

Read this: http://forums.maxima.org/7950989-post2.html

It's not exactly a bogus code, but Thorzdad encountered an issue where Nissan admitted that the parameters present in the ECU for determining when the pre-cats are no longer at optimal efficiency were too tightly programmed in some cars.

Most people that get the code get it because their catalyst has been depleted and is no longer doing what it was designed for--the secondary O2 sensor is picking up on that fact. Therefore, people buy a new pre-cat that comes chock-full of catalyst deliciousness, the exhaust gasses are once again "cleaned" by the pre-cat, the O2 sensor reads the proper difference in oxygen content from exiting the engine to exiting the cat and the light goes off.

In some instances, the O2 sensor is broken enough that it's not reporting the right voltage, but is not responding slowly enough to alert the ECU that the oxygen sensor itself has failed. Since the ECU thinks the O2 sensor is okay, it assumes the cat has failed.

Pre-cats do all of the exhaust gas cleaning until your main catalyst gets hot enough to clean all exhaust gasses without assistance.

So, nick, if the O2 sensor's value is not moving, I'd say that's a pretty sure sign it's dead. It is possible, however, that your code reader is simply not fast enough to pick up the changes in voltage that the ECU is reporting. The only true, fool-proof way to see if an O2 sensor is working correctly is to hook it up to an oscilloscope to watch the voltages fluctuate in real time.

I would replace the O2 sensors first, since they're cheap, then replace the pre-cat. Or, if you don't live in an emissions-testing state, I'd let the cat die and do the O2 sensor spacing trick with either custom-made O2 sensor spacers, or by modifying spark-plug anti-foulers and fitting the O2 sensor to them, as 99GReddy stated.

I have no idea where LightScout got the 5% figure, especially given that the way its checking that cat for proper function is by comparing oxygen in the exhaust gas before and after passing through the cat.

nicknails

Thank for the reply Eirik. I was just going through some of the live data that I recorded earlier and it appears both B1S2 and B2S2 hold steady at 0.290V. I might try recording for longer tomorrow if I drive anywhere. B1S1 and B2S1 both fluctuate between 0 and 1V, which is what I would expect.

I have to admit that this is all new info to me. I've never done much with O2 sensors or cats, everything I know I've read in the last couple days online. I would imagine that if I do replace one of the pre-cats that it would be in my best interest to go ahead and replace the O2 sensors while I'm at it.

My local Napa has a Direct Fit front cat for $267.00, which doesn't sound too bad.

nicknails

Ok, I did a much longer recording. It appears that both B1S2 and B2S2 don't start changing until a minute or two after the car starts. They look like they're both fluctuating between 0 and 1 like the other ones.

I guess that means it is the B2 Cat. Is there a recommended aftermarket cat?

AWhite1

So... along with my persistant SES light... this would likely also 'splain why my car seems to smell of unburnt hydrocarbons for a longer time after startup than I'd expect a modern OBD-II car to do.

FWIW, I'm probably one of a very minor minority of folks who is happy to see that all '01 Maxes were built as Cali-spec cars. My car was originally purchased IN Cali... but moved to PA in 2004. (That was two owners ago).

I'd hate to have a CA-spec car on the other end of the country... without local parts stocking and such!

Den

BronxSleeperMax187

Had that darn code for over A year...it disappears on its own and returns when it feels like it...i would leave it and see if it goes on its own

rvanders37

in my case with a 2000 maxima gle , 160,000 miles and p0430 code only. mind you, no multiple codes. it was the front cat converter. my car has three, a front rear and a third one about mid body...past any o2 sensors. we got the front one replaced at a muffler shop for about $450 and it was money well spent cause about three of the studs broke and they had to drill them out and put new studs in. i'd have cried if i had to do that lying on my back on the garage floor. anyway the code is gone and has not come back. there was no performance change. didn't mess with any of the 02 sensors. the front cat physically resembles a cornucopia.... minus the fruit.