goathead

I'm new to the Maxima scene so I've been searching to find what I can about this and I definitely know not to ask what fuel to run in it! So, here's some background on the issue I'm having:

Car: 2001 SE - 113k
I just replaced the plugs in it a week ago with NGK platinums. I checked all the gaps and they were at .44 so I think those are good. I also replaced the MAF meter. The car runs great, idles smooth, starts with no problem. About a day after the car threw code P0420. After looking, it sounds like I should be running at least 89 or higher and I've been running 87. It was also the 2nd tank of 87 that I've run through the car so I'm wondering if that plays into it?

I double checked all the plugs and coil packs and also checked the installation of the intake tube to the MAF and TB. Any other thoughts?

Metal Maxima

iTrader: (30)

Your gas cap is loose. Screw in better, unplug battery, and reset ECU. This has thrown 99.9% of the time I've seen it on the boards.

PS - I've been running 87 for years with no problems

oldngivout

iTrader: (8)

P0420 is the Bank 1 catalyst efficiency code. It has nothing to do with the gas cap. Sometimes it has been cured with a new rear O2 sensor, but it usually means replacing the entire y-pipe to fix it for good. The Bank 1 precat is contained there.

madsen203

I have had the same code show up... It has been at the shop for two weeks in and out trying to fix the rough shifting, lean codes from the MAF etc.

I was told the code meant to replace the front Caty and 02sens to fix the problem. I don't have $1500 to cough up to make the light go away, so until I have to pass smog, this is how I am leaving it.

After leaving it on, when I drive in the fog at night, the light seems to disappear. It has been off for a few days now. Who knows when it'll trigger again. I cannot figure out what weather/temperature/driving changes could help the problem. (BTW I am a pretty aggressive driver my self.

Has anyone else dealt with this... I also have new plugs and now a new MAF sensor and air filter. (Continuing with the 91 Chevron and Mobil1 Oil/filter)

4thgenmaxboy

The front 02 Sensor will not trip a code P0420. The rear 02 Sensor is sensing excessive back pressure from the Catalytic Converter. Most likely your going to have to dish out some money for a new Catalytic Converter. I had the same code come up on my 01 Max, and the Nissan Dealer replaced it under the emissions warranty. The emissions warranty is 8yr or 80k depending on your in service date for your vehicle.

goathead

So is it the pre-cat in the y-pipe or the actual cat in the exauhst system?

oldngivout

iTrader: (8)

It is the Bank 1 pre-cat in the y-pipe.

That is the one which you will eventually replace to solve this.

KRRZ350

iTrader: (29)

It can be caused by the pre-cat yes, and it can also be caused by either upstream or downstream o2 sensor problems. I've seen it be the o2 sensors more times than the pre-cat.

Wrong. It can and has solved it for me in the past. Research how a catalytic converter works, and how an upstream o2 sensor and a switching frequency work in collaboration with the catalytic convertor, as well as the upstream and downstream o2 sensors work to moniter the effectiveness of the cat.

It's a system, and certain faults in that system can cause it to not function properly OR think it's not functioning properly.

Double0GLE

iTrader: (1)

I had this code several times... First time I replaced the o2 sensor (I don't remember which bank or which number but it was the one behind the cat). Then I put in a stainless y-pipe (Warpspeed), it had leak and threw a code then I replaced it with another Warpspeed one and was fine for oh.. 4-5 months now it's throwing it again. Unplug the battery? =D

goathead

Ugh. So bank 1 is the bank facing the firewall, correct?

oldngivout

iTrader: (8)

Yes.

nikemike

I got the CEL about a month and a half ago. Pulled the battery cable, came back after a month. Pulled it again, came back in two weeks. First time I took it to the Nissan dealership, they said I needed a "front tube assembly" and a new O2 sensor. Parts and labor were going to be in excess of $1100. After much research, I'm under the assumption I need the B1 pre cat, as shown here: http://www.courtesyparts.com/maxima-...1981_1983.html

I found this at parts train dot com, but I want some confirmation that I'm ordering the right part: http://www2.partstrain.com/store/?N=...94965613+11921
SKU: EAST40436
If this is correct, I'll order tomorrow and then see if I "might" need an O2 sensor.

oldngivout

iTrader: (8)

That looks like just what you need. Be sure and follow up and let us know how well this fits/works. I'm sure many others would be interested in saving the money between it & the new factory pipe.

Professor

iTrader: (4)

open gas door, sticker say, For best performance use premium ^_^ atleast mine does.

nikemike

The pre-cat assembly came in from Partstrain this Wednesday and today was the first chance I had to get it installed. It was a "simple" bolt-on replacement except for one flange that had the nuts attached. I ended up just using three new bolts my dad had in his stock pile. The most aggravating part was the piece that Y's up vertically. I had to remove the studs from that to get it to swing out. They have weird hex heads but come out fairly easily.
I reset the P0420 code and now its a waiting game to see if the CEL comes back. If it does return, I'll check the codes again and possibly replace an O2 sensor or two.

If anyone has any questions, feel free to PM me. Hopefully I can give back to the site.

sascuderi

Considering how useless the pre-cats are, its a shame that they fail so early and cause so much trouble!

Anyone know why so many failures and anything that can be done to prevent it?

goathead

Sweet man, thanks. What did the parts run you?

nikemike

$301 shipped. Nissan wanted $687 for this same part.

Also, if anyone contacts partstrain, either call or do the live chat and ask for Sean. Tell them you are from maxima.org and you "should" get a $25 discount.

Thorzdad

Of course, there is also the possibility that the notorious 0420 you're experiencing is the result of nothing at all beyond a simple error in the ECU. Nissan itself has a TSB about this, and their "cure" is to flash the ECU with updated programing. Sometimes it works. Sometimes, it only works for a little while and then the code comes back.

We've had the code practically since the Maxima was new and the advice to us from different shops (both dealer and independent) was that nothing was actually wrong and we should simply ignore the light. Get it scanned every once in awhile to make sure no other codes pop-up but, otherwise, live with it.

We've had the car since '01 and put close to 300k on it with no issues. No loss of power, no hesitations or hiccups.

nismomaxx

I recently had the same exact issue... Got P0420 and it ran like ****, I also live in Connecticut...

Where abouts do you live? I cleared the code and it has yet to come back... Gascap thing is bull**** though..

goathead

I'm up in north central CT. Mine runs awesome except a little chuggy when it's cold.

nikemike

I just wanted to report back in that its been a little over a month and no CEL since. I've put a little over 1300 miles and gas mileage seems to be on par.

So far so good!

colbertk

the pre-cat in the y-pipe or the actual cat in the exauhst system?

KRRZ350

iTrader: (29)

Last month I actually just fixed yet another p0430 on an 01ae, car had sims put on it by the owner to try to fix it, didn't work. Replaced the primary o2 and it's good now (The code was very consistent, it was there 100% of the time for him)

Oldnewbie

FOR 5TH GEN MAX'S REGISTERED IN CALI:
Help!.
(Apologies for posting here - I wanted to start new thread on this, but I don't have permission)

A new Cali cat law went into effect Jan 1, 2009. It appears to be killer and I'm in the process of finding out the hard way.

(Mine is a 2001 Max SE, 5-Sp, Stock, 108 Kmiles, regularly serviced, synthetic oil, running Cali ethanol-laced fuel - agressively, but not abusively driven w/mostly freeway and long-distance trips across country)

The "service engine soon" light turns on so, the next day, I go to my Nissan dealer. He checks and says that BOTH cat converters are bad and hands me an estimate for $2.3K to include both cats, 2 new rear O2 sensors (says the rear sensors are "starting to move slow") and installation. [How likely is it that both would go out together and both would have cheesy rear sensors? My background in stats and electronics says, not very likely, but I need advice from more experienced hands here]

My Kragen parts guy tells me that the O2 sensors are probably due to be replaced at 108Kmiles anyway. [Is that true?]. He wants to sell me new 3 Bosch sensors for $100 each (Sensors aren't mentioned in the law), install those, and see if that clears up the problem. [thoughts?]

Here's the horror story - see following link for the bad news for 5th Gen Max drivers registered in the state of California.

http://www.car-sound.com/04basics/04california.asp

As i read it (and anyone correct me if I'm wrong), the new Cali law (probably written by the car dealers w/repair shops) in effect, says that for our aged cars registered in the state of CA, you must have an OEM cat OR a cat that is specifically approved in the state's list for your specific make and model of vehicle and those parts must be labeled for easy verification according to the Cali law - in order to pass your next smog-check for your next year's registration. IOW, meeting the exhaust emission standard isn't enough, you have to meet it with state certified parts. However, THERE ARE NO APPROVED AFTER-MARKET CATS FOR THE '01 Max (probably, not any of the 5th Gen Maxis either) in their list which means you must use Nissan parts. Checking the major after-market cat sources (Magnaflow, Discount Converter, Ltd. etc), none show any Cali-approved converters for Cali-registered '01 Maxis.

With the Nissan dealers' high prices, it means that for Gen 5 Maxs that have not had their cats replaced, everyone has to knock about 1500 bucks or more off the resale price of their cars (anyone buying one in Cali had better check to see if it's been done.) I have no idea how they might or might not "grandfather" people who changed theirs to non-Nissan brands last year or earlier.

(Almost) any advice is welcome - no, I don't want to try to beat the check with simulators etc. The fines are too high for getting caught here and the law places all the burden and penalties (strict) on the intallers and the smog check guys, so they will be checking.

IHAVEA2KMAXIMA

iTrader: (7)

OldNewbie:
I heard about the new Cali emission law too but not exactly 100% sure if it's true. Anyways... if your precats are bad, you can order a new y-pipe from Dave B the parts guy for $600 IIRC and o2 sensors for $80 a pop. I think the o2s are common to crap out at that mileage so it's a good time to change them out.

Also I had p0420 quite awhile ago and I thought it was because of my aftermarket y-pipe. I put my stock back on, p0420 came back. So I went to the dealership and got my software updated because there was a TSB on it. So far no CEL

Jordan22

dude ive had this problem any heres the solutions i found have been working i have an 01 SE with 107K ... first you can start by replacing whatever sensor is failing but what happens then is it just fails another one down the line so i have replaced sensor 3 and 4 its the white and gray one you can buy those online just dont get universal it must be a bosch there expensive but easy they all our easy enough to put in urself. then for the other 2 you have to go to the dealer dish out 175 a pop i havent done that yet. so what i did was unscrew each one the red and blue sensors and steel wolled them and sprayed them with heavy duty cleaner and pretty much made the tips look new again. put them back in clear the code urself and it works for months but in the end you really just have to replace the sensors. in the mean time get an OBD-II sensor and you can just clear the code whenever it comes up so you can still pass emissions. its a pain in the butt dealing with these but DONT LET ANYONE TELL YOU YOU NEED A NEW CATALITIC CONVERTER they are super expensive we have 3 in our Maxs the one that fails first is 610 installed i looked into it. THEY HAVE TO REPLACE THE SENSORS ANYWAY when they put in a new cataltic converter so better off doing the sensors urself first then going out all out with new cats

nikemike

I was skeptical to replace any parts when I started getting the P0420, but I was told by several reputable mechanics that O2 sensors are fairly basic and generally don't fail. I opted to go the route that I posted about and get an aftermarket y-pipe. I never replaced the O2 sensor(s) that the Nissan place wanted to, and so far, no more P0420 codes.
The only true way to find out if you are having cat problems is to have the pressures checked b4 and after, which from my knowledge, only a Nissan dealer can do.

Oldnewbie

IHAVEA2K... TY for your response.
I assure you, what you've heard about the law is true.

Re aftermarket pipes: I'll have to check Dave B. --- but, what is worse about the new law (for others here who have aftermarket exhaust systems) is in the details of the link that I posted. Replacement parts must be positioned close to the original positions - within inches. They've crafted the wording of the law so tightly that only the most popular brands and models - with largest market potential - will probably ever be manufactured and distributed by aftermarket vendors. (it's blatant highway robbery. If they really wanted to regulate emission gases, they'd stick to measuring emission gases and not rip off everyone, using the trickery of the relatively very few who will always try to game the system, as an excuse. And they wonder why people are moving out of Cali)

TY for the heads-up on the TSB. I checked and my S/W is updated.

Oldnewbie

and, herewith, the probable motivation for my Cali dealer's aggressive checking of my '01 Max SE's emission monitoring... and, their high prices for cat replacement - trying to make up the $4.4M fine. This gets suckier every day... (see my previous posts)

Just found...
Release 09-35
FOR IMMEDIATE RELEASE
April 16, 2009
Karen Caesar
(626)575-6728
www.arb.ca.gov
Nissan Motor Co. fined $4.4 million
Automotive giant cited for failing to monitor car emissions

SACRAMENTO - The Air Resources Board last month fined Nissan Motor Company $4.4 million for failing to meet requirements concerning the diagnostic equipment that monitors tailpipe emissions on most of its 2005-2007 models - more than 450,000 vehicles.

On-board diagnostic systems are incorporated into vehicle computers to ensure tailpipe emissions stay at permissible levels. If a problem is detected, the system turns on a "check engine" light to alert the driver.

The ARB discovered Nissan's problems in 2007 during a routine compliance review. The problems concerned inadequate monitoring of engine sensors that govern proper fuel system operation and whether monitoring takes place as frequently as required.

"California advanced the goal of clean air by pioneering the development and use of the on-board diagnostic system to make sure drivers know when their emissions equipment malfunctions," said ARB Chairman Mary D. Nichols. "We consider it to be a vital tool not only for consumers, but for all of us who want to breathe clean air.

"Nissan has been cooperative during this investigation, and we are confident that the design process changes they implemented will prevent future problems," Nichols added.

Nissan's settlement with the ARB requires it to pay $3 million to the California Air Pollution Control Fund, which provides funding for projects and research to improve California's air quality. It must also pay $1.2 million to the Environmental Education Initiative and $200,000 to the National OBD Clearinghouse.

California has the nation's poorest air quality. Excess vehicle emissions can cause or exacerbate a host of respiratory and cardiac conditions and pose a danger to public health.

The Air Resources Board is a department of the California Environmental Protection Agency. ARB's mission is to promote and protect public health, welfare, and ecological resources through effective reduction of air pollutants while recognizing and considering effects on the economy. The ARB oversees all air pollution control efforts in California to attain and maintain health based air quality standards.

IHAVEA2KMAXIMA

iTrader: (7)

If you can't afford new precats, you can get o2 sims (might not pass visual test if your station is thorough). Since your software is already updated, try changing out the o2 sensors or something.

Oldnewbie

IHAVEA2K... As I said, the law punishes smog-check guys (and installers) who don't measure up (see their $4.4M fine against Nissan mentioned above), so they will be checking close or risking the loss of their lucrative smog-check licenses. I'm off to Autozone tomorrow for their read on it and, as you suggest, that will probably involve new O2 sensors first to see how that works before going further. Pre-cats or cat, it will still require pricey "genuine Nissan parts" for those, if necessary. TY again.

Oldnewbie

Hurrah! Update and good news, for a change.

After posting my last, I did some research and came to the conclusion that cats on a properly maintained, properly driven, and un-abused car should last for the life of the engine.

On reflection, I remembered that when the price of 91-octane had gone above 3.50/gal about a year ago, I had drastically changed my driving habits. Previously, I'd kept the rpms above 2K - even when just tooling around town on errands. but I had changed to shifting early, holding rpms down and keeping my foot off the accelerator, as much as possible, to save fuel.

So, I resumed my old habit of keeping my rpms above 2K and voila - the "service engine" light went out two days later. A month and 1000 miles later, with many start-ups, the light hadn't come back on, so I went in for my smog check. (BTW, If the error condition is not detected by the engine computer over several dozen start-ups, it automatically clears the error code from its memory)

It passed the smog check with much room to spare. Actual emission levels were only 1/5 to 1/4 of the allowable maximums for my Max. That proved that my cats were performing optimally and that my assumption about healthy cars and healthy cats is still to be disproved.

Following that, I went on a 5K tour of the west and north-central states with a lot of interstate driving at about 80-85 mph, mountain driving to over 11K ft alt, blistering heat (118 deg) - everything - and the light hasn't blinked. (oh, ok, I also pushed it to 140 mph w/150 lbs in the trunk just to see if the old dog could still run - whoopee, it can)

While this is working out well, it doesn't prove that the sensors shouldn't be replaced before they do real damage. I'll let Nissan do my upcoming oil change and ask them to check the sensor-function again just to see how they look now.

The Nissan mechanic keeps claiming that the light will come back on again - he's wrong - and that the cats on "my car's year" usually go out between 80K and 120K miles. I think what he's missing is that 95% of all '01 Maxes were automatic transmissions. They probably up-shift early under average acceleration causing lower gas flow at lower temps through the cats - which are both unhealthy for cat longevity. I'm going to win this bet and, even, if I don't, I'll have dodged a $2300. repair job in the meantime. Maybe I'll replace the sensors, but I'll wait to see how they test.

Also, this does nothing to change the new crazy-*** Cali law on catalytic converter replacement and the down-pressure it puts on all 5th Gen Maxs' resale values in Cali. My advice to anyone wanting to sell a Cali-emission, Cali-registered 5th Gen Max is to take it out of state to sell it (if they have not already replaced their cats with new Nissan parts and have the service receipts to prove it).

If anything goes south, I'll update again. Thanks again to all for their info and advice. I hope that my experience gives others some insight into the situation here in Cali.

sontakke

There is some truth to your method. What I have found is that if you flog the engine the catalytic converter monitor test does not run. So I could keep the light off for a while but as soon as I start driving gently the light would trigger.

If you have a scanner, you can verify if the cat converter monitor test is completed or not. If the test is completed, then you are home free and your technique has caused the cat converter to gain efficiency.

I believe these days, many states allow one or two incomplete monitors for you to pass the emission test. That way you can still get the inspection done before the light triggers on but you have to time it just right!

- Vikas

Oldnewbie

TY for the thoughts Vikas...

I think I'm on the right track. It's been over 4 months and 7K miles with hundreds of gentle starts and warm-ups - my habit, without a flicker. When the light was on and Nissan said everything was bad, I didn't "flog" it, I just started letting the rpms run up higher before up-shifting and down-shifted whenever they fell below 2K rpm. I do run the tach out to red-line under full power once or twice a week in 1st and 2nd just to check on the integrity of all parts in motion, but not habitually.

Fortunately, I didn't have to play the monitor/timing game to pass the smog test and, having passed it, I'm good for another two years.

- John

sontakke

You are absolutely right about the 2K revs. I remember the day before my inspection and few feet from my house the light turned on as I let the RPM drop to 1K before shifting. For the entire week, I was deliberately keeping it over 2K.

For example right now, it has been at least 4 days and more than 10 trips but my Cat Monitor is still incomplete after reset. It will be a race until P1320 trips or I/M completes. It is one of the rear coil and I have been procrastinating changing it as the code is pretty random and not that frequent. As far as P0420 and P0430 are concerned, I *think* I have taken care of them.

Fortunately, I just passed my smog, so I am good for only another year. In Mass now they smog every year.

I do wish I can nail down why on some start I get extremely super quick throttle response and some time not so quick. Funny thing is I end up driving slowly when the throttle response is great. I don't need to "verify" that everything is working when it jumps from 65 to 70 if I feather the gas pedal. On days when the throttle response is not that great, I end up driving over 80 to reassure myself that it is still fast just not as as fast as it was couple of start ago :-)

- Vikas

Oldnewbie

Vikas... Glad you made it through the smog check.

I can't give you much insight on your throttle-response (mine's a Cali-emission version anyway, so might be quite different) although an intermittent coil problem would be expected to effect power as well as the gas-mix, -flow and -temp hitting your O2 sensors and cats - maybe they're all related. The scariest things about these more advanced emission control systems are all the possible interactions between all the parts which makes it easier for a repair shop to just start recommending replacing (expensive) parts (at your expense) until they stumble on the soluton.

There are a lot of guys here that are more familiar with ins and outs of the computer, MAF, sensors etc than I, so maybe someone will read your post and respond.

Good luck. - John

sontakke

Mine is Cali-spec too; I suspect most of these cars are Cali-spec as far as I can remember from reading this forum for last 8 years.

- Vikas

Oldnewbie

Vikas... I checked. The 2000 year came in a "Federal" and a "Cali" version, while all the 2001s and 2002s sold in the U.S. were "Cali" spec. I'm not sure about the 2003s, though I believe they were Cali spec too.

Oldnewbie

Followup on my post #32 above - Smog techs on the legal hook for enforcing CA smog check laws...

As I said...

"(10-21) 18:12 PDT San Jose, Calif. (AP) --

Some technicians at seven Santa Clara County smog check shops are facing jail time after being convicted of illegally certifying vehicles that did not meet clean air standards.
More News
Santa Clara County prosecutors say 12 technicians were convicted of falsifying certificates after getting caught in a sting operation by the DA's office and the California Department of Consumer Affairs' Bureau of Automotive Repair.

DA spokeswoman Amy Cornell says 10 technicians are facing one to four months of jail time after being convicted of felony charges. Two technicians who cooperated are expected to be given lighter sentences after being charged with misdemeanors.

Authorities say five of the shops involved in the sting were in San Jose, one was in Morgan Hill and one was in Santa Clara."

---Information from: San Jose Mercury News, www.sjmercury.com
Read more: http://www.sfgate.com/cgi-bin/articl...#ixzz0UhfEJs2M