Oldnewbie

Well, it's 2010 today and my odometer shows 122K miles. About 10K miles following my last episode with service-engine light (above), it finally came back on again. I checked the code and it was the same, so assumed that it was one of the trailing O2 sensors again.

Note 1: With the new Cali law, California Autozone stores no longer loan out the ODB2 check-meters. So, with a neighbor, we bought a cheaper "CanOBD2 Car Reader". It reports 11 monitor statuses, pending codes, active codes, and will clear codes, all with "ignition-on/engine-off", but does not do the more complicated "engine-on" tests that are follow-on tests after making repairs. Additionally, two Autozone clerks told me that they had cleared their stock of aftermarket cats from their shelves after the new law came into effect (although I'm not sure if they will still re-stock aftermarket cats that are "approved" by the state and with the new labeling which, in any case, won't include those for 5th Gen Maximas, as they have not been approved by the state).

So, I had Nissan replace all four O2 sensors at my last oil change and have no lights or codes after about a month of driving - with all computer-monitor tests having gone to completion. As I suspected and suggested, my cats are fine. I went for all four as every mechanic I spoke to said that they are usually good for only 80-100K miles and, rather than keep stumbling on one after the other, I decided to replace them all at once.

Note 2: Nissan required an engine-computer ROM update when replacing the O2 sensors. I haven't tracked down the technical note for this yet and I don't know whether it's a necessary update for performance, which I doubt, or, more probably, just convenient or required for Nissan's engine-analysis systems. The Nissan service rep was foggy on the change and reason for the update.

Happy New Year to all

sontakke

For 3 months you had no CEL; if I were in your shoes, I would wait at least that much before declaring O2 sensor replacement is cure of P0420/P0430.

For me, I am still on my original sensors at 141K miles. I did add couple of shiny stainless steel parts ($15 each) and they are doing their job as intended :-)

- Vikas

Oldnewbie

Vikas, Glad you have done so well and hope mine keeps going too. I'm pretty much going by the actual smog test data - taken early in this episode - which showed (after my first SES light and Nissan dealer's diagnostic) that my cats were performing extremely well (Nissan just looks at the sensors and codes, not the actual gas coming out). All values measured in the smog test were only small fractions of the allowable amount for my model, so I started into this knowing that at least the cats were doing their job.

I don't assume that my situation is the same as everyone elses - that sensors are a universal cure-all for all P0420/P0430 codes, but I think in my case, they were all that was wrong.
(Furiously knocking on wood, here)

Take care... John

sontakke

The thing is even with P0420 and P0430 codes, the smog results will be stellar. It has been documented and if you search internet, you will find many reputable papers to that effect.

Our state no longer does real emission; it is only hook up the OBD-II these days.

- Vikas

Oldnewbie

Cali still does both - double jeopardy, as it were.

But, as long as I have the physics and chemistry (controlled by the Gods) on my side, I can whip the electrical engineering and computer programming (of mere mortals) any day. LOL (I used to design and build high-speed data-acquisition-and-control systems as means for doing even more complicated things). As I have another 17 mo. before my next required smog-check, I have lots of time to "work things out".

I'll just put you on the side of my Nissan mechanic who predicts doom and gloom, if I don't cross his palm with another grand and a half. (Just kidding - about putting you in his camp)

Kidding aside, the real problem is that the manufacturers are using the increased complexity of computer control systems (really not all that complicated - except, maybe, to Toyota) to hide the whole thing from the end-users (their customers) and make their products proprietary after-warranty cash-cows in their parts, repair and maintenance businesses. When they get dumbed-down legislators to endorse and enforce that proprietary regime on car-owners, as they have in Cali (with its "only OEM or state-approved after-market cats" and precious few of the latter), then all of a sudden, all cars out of warranty become extremely expensive to own and license. (Pity the Beamer drivers with dual exhausts and 4 cats - about $3600 in parts alone for cat replacement - and that on the basis of idiot-lights owned and controlled by BMW instead of actual pollutants passed).

As the whole enterprise is supposedly aimed at reducing pollution and environmental degradation, it's ironic that such laws will greatly increase the turnover-rate of car ownership which is far more environmentally destructive than buying quality and being allowed to drive it to the grave. Oh well

-John

sontakke

The thing about P0420 and P0430 is that cat converter efficiency is *inferred* and not *measured*. The threshold for that algorithm is really tight. As a matter of fact, if you try to get warranty service for those codes under EPA mandated 8/80K, Nissan relaxes the threshold a little bit by reprogramming your flash. If that gets the car out until the 8/80K expires, Nissa saves money!

Does California puts the car on the dyno and goes through the whole Federal Test Procedure (FTP)? The P0420 and P0430 tests are only run when the car runs at constant highway speed for few minutes and then decelerated by suddenly closing throttle for a while. Even if the O2 waveform does not make the programmed stringent cut, the emission would not increase by much because the converter is still operating at say 89% efficiency versus 90% threshold.

As I have repeatedly said, the entire P0420/P0430 business is a racket. But it is good for economy as it pumps lot of money in to it :-)

- Vikas

Oldnewbie

Yea, yea and yea. No sooner had I posted my last, when the agency from hell (CARB - Cali Air Resources Board) announced that they had tested a sample of recently smog-check-passed cars and found them to be in violation of emission standards, apparently proved that some smog-check stations were falsifying test results, and are taking the latter to court.

Further, and acting with apparent irrationally as only CARB can, they decided to introduce legislation, not to attack the problem - i. e. crooked smog-check-station operators, but make it worse. The proposed legislation would do away with the direct emitted-gas measurement altogether and "use only the on-board OBDII system to verify the performance the the emission control system".

Now if that passes - and agreeing with your comment above about inference vs. measurement with tight algorithms and not to mention programmable hanky-panky, the fox (car companies) will have been granted complete control of the chicken coop - with we being the chickens. Dealer's service departments will be the only legally-recognized source of judgment (though the algorithms they use) for what needs to be done and your dealer's parts department will - except in relatively few cases not including older Nissans - be the only legally-recognized source of repair parts.

First, as your comments states, the OBDII cannot measure exhaust "pollutants" and second, the "decision" as to whether car-owners will or will not be gouged for expensive cats and sensors, that they may or may not need, will be completely at the discretion of the car companies (who control the dealer service centers) and bundle their actual "policy" in nearly indecipherable computer code hidden within your engine-computer's non-volatile memory.

CARB corruption (I haven't checked the political contributions/connections lists yet), incompetence, or both? The substantial monetary benefits to the car companies at the expense of independent service stations, aftermarket vendors, car owners, and the environment make me think the former. Nobody could be that dumb. The only other explanation is that CARB is on a mission from their gods to make car ownership in California - arguably the most car-dependent society on the planet, uneconomical. But, as I've pointed out their action makes no sense from an environmental standpoint either, so it keeps looping back to corruption at some level. ---John

sontakke

Do you know if sensor extensions are caught by the inspection station?

Oldnewbie

Are you referring to sensor simulators - that produce voltages similar to a properly operating sensor? If so, no. I've never tried them and don't know anyone who has. Other posters here do discuss them though.

As an aside, if they work to suppress an error code and SES light AND your inspection station only checks the OBDII for codes (and not actual exhaust gases), then they should work - and, if they and their electrical leads and plugs don't stick out like sore thumbs on an under-hood visual inspection.

Here in Cali, some of the stations are running scared of the new laws and differ on what they'll pass and fail. My neighbor was failed just for having a non-OEM air-intake duct and filter on his Nissan truck, even though everything else checked out ok (the mechanic claimed that any modification of the OEM setup of intake/exhaust was not allowed - which isn't exactly true. See my previous reference to the law itself). Many other stations would not have failed him for that.

sontakke

No, I am NOT talking about the simulator. I am talking about spark plug anti-fouler which extends the O2 sensor by about an inch. This is $5 item purchased from local auto-parts store but needs little work or you could buy a pre-fabricated one on ebay from $10. Better quality stainless steel will cost you about $15-$20.

I could never understand the people who put electronic simulator where a mechanical extender would have worked fine.

- Vikas

Tee00Max

iTrader: (18)

So if I have this code, i need to place the non-fouler in which o2 sensor hole??

Thorzdad

This.
I am consistently amazed how many pixels have been burned here and in other forums about the P0420 issue...and how much money people have burned to replace perfectly good cats. The "error" is not any indication of a real problem. It's a software issue that does not actually affect engine performance. The only effect is a constant check engine light. All you ever need to do is to occasionally pull the codes to make sure something else hasn't cropped-up. Otherwise, there's really no reason for all the stress over the P0420.

We've put over 300k on our Maxima and it's had the P0420 code since about a year into our ownership. It runs as well as ever. Yeah, it's kind of a pain to always have that CEL in your face all the time. But, it's sort of part of that 5th-gen Maxima ownership mystique.

sontakke

I hope you do know the cheapest way to avoid the constant P0420 in your face. It works.

- Vikas

Oldnewbie

Oh. Ok. Thanks a lot Vikas, I'll look into it.

- John

Oldnewbie

Apologies for any excess pixels burned on my part, but I was trying to address something that, apparently, you are not faced with - an aggressive state program (Cali) on auto-emission control that does not allow (fails vehicles with) error codes or monitor tests that have not run to completion. I agree completely with your estimate of the relevance of the PO420 code and doing so has saved me $1500. on replacements that my Nissan dealer said I needed. I might have been able to save more, but that was my choice.

sascuderi

Same in NJ. The situation is not just having to look at an annoying light; you can not past inspection if the light is on. So you have to either fix the problem or take your car off the road!

Thorzdad

Yeah, my bad. I apologize for being so harsh. You are correct that, here in Indiana, we do not have car inspections (except, apparently, for a small area in SW Indiana, so I'm told) I always forget the inspection issue.

Oldnewbie

No problem... Appreciate and agree with your other insights into the cat-code problem.

And, as you and I both have '01 SE 5-speeds, I REALLY appreciate reading that yours has gone over 300K miles and I've only racked up 120K+ so far

If you trace back over my previous posts, you'll see how wacky the Cali CARB regulations have become.

Thorzdad

120K is just barely broken-in on these engines. Just keep changing the oil and all should go well for you.
I hear you about those Cali CARB regs. I'm of two minds on such things, though, as I'm old enough to have seen what the air over places like LA used to be like back in the bad old days of the 60's and 70's. You have my sympathies, though, since you're dealing with an issue Nissan refuses to acknowledge and fix, forcing guys like you to burn cash and take all sorts of unnecessary measures.

sontakke

I have three vehicles built in 1999-2000. The lowest mileage is 141K. They all had the P0420/P0430 errors; some starting at 65K on the clock. The 1995 Camry started throwing out the P0420 at 145K, we bought it at 135K and I recall the used car dealer had changed the timing belt and had put on the new converter. I suspect it was NOT Toyota OEM. The OEM should go for at least 60K.

It is not only Nissan or Honda or Toyota which starts giving spurious P0420 errors once the car has over 60-100K miles.

- Vikas

Oldnewbie

Well, it mid-year. With 130K miles on the odometer (22K miles and 14 months since this episode began and 6 months/8K miles after replacing all 4 of my O2 sensors) and no more "cat" or "sensor" codes.

I have had some more sloppiness problems with my Nissan repair service though - besides their high prices, so all-in-all, I'm looking for another shop in the San Diego area.

Sowfpaw

Hi all newb over here and an avid forum poster. I also happen to be the Catalog Manager at Eastern Catalytic. I have read pages of threads and Q & A on this board and wanted to take a moment to shine some light on this issue that has factual bearing straight from the source. In regards to the P0420 & P0430 codes, of course everyone who has an issue with these codes has their own unique situation and circumstances when it comes to SES lights. However, there is a bit of information I believe was left out here even in the most descriptive replies that may help you out when determining what exactly your causes are.

First and most importantly, no vehicle in history has ever had a direct reading from a catalytic converter. Not even from a converter mounted 0/2. What I mean by that is whenever you trip the codes, they are directly based off of the 0/2 sensor reading. I wont discuss up or dowstream 0/2 reading as that is not the basis of my post although it is important when factoring in certain instances.

My point is simply that whenever these codes appear, it is because there has been an out of allowance reading detected in the exhaust system. Where as the rear 0/2 may trip the code or the front just the same, it is simply indicating that the closest component is not within its allowable range of acceptance. This methodology applies typically to 49 state vehicles not equipped with CA emmisions. There was an above post explaining in detail about the CA requirements and issues of parts availability and ability to interchange a standard direct fit system. There are only a select few companies Eastern being one of them, that are permitted and equipped to install components on CA cars and meet ARB certifications. This doesnt mean that if a Ca vehicle registered in AZ wont have an emmisions code. It means in conjuction with the A.R.B. (Air Resource Board) or formerly CARB, the converter itself is equipped with the amount of substrate material required to depleat emmisions enough to meet the standard.

Until 2009, vehicles were not all made the same in regards to emmisions. A manufacturer such as Nissan in this case, designed their vehicles to be sold within the 49 state area and specifically programmed and equipped vehicles were able to be sold in CA. The ECU in those Ca vehicles, had a stricter set of allowances obviously to accomodate the ARB and stricter emmisions. Some had also said that a reflash was the cure all. Thats again is only a partial fix.

The correct repairs in most cases are the following:

1. Inspect the converter on the exterior first looking for any heat deposits or damage and internally by shaking the converter and listening if the substrate is broken similar to testing a light bulb. (it is possible excessive rich and lean conditions can cause the converter to burn up or not properly heat up)

2. Replace if needed

3. Now that youve either had to replace a converter or you found it was ok internally by shaking it to hear if the substrate has broken, you can start addressing the cause of the problem. A converter will almost never fail solely over time w/o alternate factors.

4. Perform a test on ALL 0/2 sensors, A/F and visually inspect EGR components and replace if needed, I would always recommend replacing the 0/2's all at once to avoid durability issues in the future.

The reflash outside of Ca will just simply put a base 49 state tune which is prob a good explaination for those who have replaced the converter as to why they have noticed performance gains. This also applies when replacing a Ca system with a standard 49 state system. VERY IMPORTANT thing to remember as well is that in a lot of cases even the piping fitment is different. So as I said earlier, if you take a vehicle that was registered in NY but was built to pass Ca emmisions, it is a strong possibility that the codes will return unless either a Ca converter was replaced or the vehicle was fitted with a 49 state emmisions system AND a 49 state tune. In most cases converter is not bad, but because your ECU has detected an exessive amount of emmisions based on its preprogrammed maps.

Of course I sound partial here as I am sure most of you are saying by now, but this is not a post to sell you on a brand or part. This is simply some information that should ALWAYS be considered when addressing codes like these. Mechanics being a big time contributor will often be quick to blame a converter based on a code. But I hope you now can explain to them why he/she more times than not is WRONG!!

If you would like more info on this post or have any questions please feel free to EMail me @ Asatzman@easterncatalytic.com

Hope this helps!!

sasha

This is my first thread and I want to thank everyone for their input and for providing so much useful information and to share my experience with the P0420 and P0430 codes.

I have 2k maxima with 175k miles with original 02 sensors. I've had to go for inspection in NJ recently and needed to clear the P0420 and P0430 codes.

For the P0430 code, I ordered the Eastern Catalytic converter found here http://www.performancepeddler.com/de...CT_ID=EAS40387 then cleared the computer and only the P0420 code popped up.

I had the nissan dealer update the ECU (they already were aware of the TSB out and had a more recent copy). The car normally reset after about 50 miles of driving but after the ECU update I drove about 500 miles before it reset and no codes came up. This was recent so its too early to say how long they'll be gone for, but it worked for now.

Also for those in NJ, you are allowed to pass inspection with 2 system in the not ready status, so long as the catalytic system is not one of them. Unfortunately for me, the cat was the last to become ready.

Scottwax

iTrader: (8)

Replacing my precats got rid of my P0420 code. I got some lower mileage used ones from a fellow .org member who put headers on his car. Both precats showed signs of deterioration and my car was about 2.5-3 seconds quicker from 45-85 after replacing them. My car had about 162k miles on it at the time.

Oldnewbie

As of June 1, 2011, 143K miles, went in for a Cali Smog Test (exhaust metering) and passed cleanly. No more codes and cats are healthy - as I have been saying all along.

sticky

ok people you dont need to replace your cats precats,with your 420-430 02 sensors codes,dump a gallon of laquer thinner in half tank of gas once a year,cleans cats 02s injectors all your smog, cel light goes away pass clean inspection,will not harm gas engines,never a cel light or problem with my 01 se cali max

sontakke

I know Scotty recommends it but do you have personal experience with it?

jaboogie

Hey, I own a 2000 maxima se...the car has recently been running a little rough and the check engine light came on...I took it to autozone and had them diagnose it and I got 3 codes...P1320, P0420, and P0430...they gave me a print out explaining what the problems might be...i then took it to my mechanic who hooked it to his diagnostic reader and the only code that appeared was the P1320...he then said the misfire was coming from coil #2 so he replaced it and cleared my check engine light but the moment I turned my car off and turned it on the light came back on...I am so stressed right now...is it possible for those codes to just disappear like that?...and can the P1320 code be something else besides the coils?....PLEASE HELP!!!!

Thorzdad

I've said it before...you can happily drive around and ignore the 0420 code. Our Maxima has had that code since it was new. No problems. The CEL being on all the time is a pain, of course.

CTMaximaSE

How's your air filter ?

Oldnewbie

It's Feb 3, 2012, with 158K miles (25 months and 36K miles after replacing O2 sensors) and everything is still running smoothly. No codes. I win. (see my previous posts this thread)

Off topic: Now I'm really pissed. Nissan replaced my stater at 130K miles (original starter) for a big price and it went out at 150K. They wasted 2 hours of my time to tell me it wasn't the starter, but after I had more trouble and went back a second time, they said it was. They replaced it and, again, charged a high price (full price for starter and labor) that they refused reduce even though it was their OEM starter, installed by them, that went bad after only 20K miles. Now I have to find another shop that I can trust locally in San Diego. Sorry, had to rant.

sween

@oldnewbie Sorry for the long nOOb post, but I'm having the same issue with my '00 Max SE 5 spd (136K miles) and also live in SD. My registration expired in Oct. '11 and I've spent nearly $1k trying to sort my car out. Originally it threw codes for the IACV (which I replaced, and also cleaned my throttle body in the process), a bad MAF sensor (which I replaced), and 2 O2 sensors (which I paid Nissan $350 to replace). Can't remember which 2.

I tried to smog it after Nissan replaced the O2 sensors and reset my computer but failed because the sensors weren't ready (I drove it nearly 300 miles before I took it in). As soon as I left the smog station the light came back on. My failed smog results show that I actually passed EVERYTHING with flying colors except the 3 sensors that weren't ready.

I took it back to Oceanside Nissan and they told me it was throwing code P0430 and P1706. They quoted me $1300 to fix both. I've been researching a solution for a while now but haven't decided on what to do, as I don't want to just flush $1300 down the drain. I'll have to replace the p/n switch for code P1706, but I would like some advice from a fellow Californian about the other code...... Currently I'm running 87 octane and drive very conservatively since gas is so 'spensive. Should I try 91 oct and drive like a bat out of hell for a while and see if it clears? ANY advice is appreciated

Ghost_54

iTrader: (13)

sween, you should be using 91 octane all the time in the VQ engines. As for the P0430 that is the bank two (located just infront of the rad) pre cat that is becoming clog a change of fuel will not resolve the clogging, however the engine general will perform better. You can either gut the inside of the precat out or replace it. If you have already replaced the o2 sensors then those are about the only two options left unless you are thinking of installing headers & Y pipe which will take care of the removal of the precats.

Oldnewbie

Well, I'm at 175K miles and just passed my Cali smog check - again. That's 4 years and 67K miles since I was told by Nissan that my cats were shot and needed to be replaced for $2k+.

However, it threw a 420 code 6 weeks ago, which I cleared. It came back 4 weeks ago and I cleared it again. It hadn't showed up again, so this time, and as my biannual smog check was due, I paid a little extra and had a (good) independent smog check station do an efficiency check on my cats (I was trying to figure out whether it was the sensors again (all replaced in 09 at 122K miles) or the cats.

The results explain what others have pointed out here. There were no OBDII codes, all tests had gone to completion, and the exhaust HC(ppm), CO(%) and NO(%) were well below the "maximum allowed" by CA for my vehicle (thus passing the CA test - yeah). However, while the efficiency tests showed the sensors operating properly, they also indicated that my cat efficiencies were pretty far below their design specifications (and presumably going down). The latter was what tripped the 420 code and will likely trip it again. There's no risk in running the car as is (as others have pointed out here) and I have two years before my next required smog check.

So, yeah and boo. If I still have the car in Cali two years from now, I'll likely have to replace the cats before my smog check then. But, that will be 6 years and probably ~100K miles after I was told that they had to be changed by Nissan.

Added note: At the time of my last post, the California Air Resources Board (CARB) had not approved any aftermarket cats for the '01 Maxima, but that has changed. They now allow cats and pre-cats from two after-market companies (Magnaflow, which I'm familiar with and Valina Inc. which I'm not), but (there's always a but) the Magnaflow cat is a "universal" type which means there are only straight pipes on either end - they don't have bolt-on flanges like the more expensive OEM cats and would require either welding in place or welding bolt-on flanges on either end. The labor cost of welding, unless you do it yourself and don't value your time, would probably outweigh any difference in the parts' price. Some I've spoken to also believe that the Magnaflow cats, while good, are not as efficient as the OEM cats (but, my bad experience with the Nissan OEM starter causes me to be skeptical of any such claims any more).