DTC Codes: P0420 and P0430

Hello All...

New to the forum.....

I have a question regarding my 2001 Maxima SE. It has 162,000 almost trouble free miles.

My check engine light is on, and I am getting Codes: P0420 and P0430, Catalyst Efficiency below Threshold Banks 1&2

The dealer says I have to replace both catalytic converters and all FOUR O2 sensors. That runs almost $2800 total...

I really don't think its the catalytic converter because she's running strong as ever and I have not smelled the "sulfur" smell as i've read from the other posts.

Anyone might know how I can begin to trouble shoot this??

Much Appreciated!

[NissanTech]

For engine light diagnosis check the information in this page:

http://www.nissanhelp.com/Ownership/Maxima/EngineP.htm


and for more information in that particular code check this bulletin (make sure you read the entire bulletin):

http://www.nissanhelp.com/Ownership/.../NTB00-070.htm

I just got this the other day. It went away when I shut off the car and hasn't come back on since. Could it just be a fluke?

[NissanTech]

Yes, for some reason the information that the ECM reads got out of range. If the code ever comes back I recommend reprograming the ECM to the latest program before replacing any parts.

[jjack]

I'm also getting the p0420 on a 01 maxima. Is the ecm reprogramming a nissan covered procedure? It only has 42,000mi.

[NissanTech]

No, unfortunately is only cover under regular warranty. Is not that expensive, most dealer will only charge you around 1.0 hr of labor.

Do you have any kind of extended warranty? Some extended warranty will cover the reprogramming.

[mpe235]

The reprogram is covered by an 8 year 80,000 mile warranty.

[flutie845]

Originally Posted by Anonymous

Hello All...

New to the forum.....

I have a question regarding my 2001 Maxima SE. It has 162,000 almost trouble free miles.

My check engine light is on, and I am getting Codes: P0420 and P0430, Catalyst Efficiency below Threshold Banks 1&2

The dealer says I have to replace both catalytic converters and all FOUR O2 sensors. That runs almost $2800 total...

I really don't think its the catalytic converter because she's running strong as ever and I have not smelled the "sulfur" smell as i've read from the other posts.

Anyone might know how I can begin to trouble shoot this??

Much Appreciated!

I had the same codes on 2000 maxima.I allso had a bad coil on # 6.I replace the bad coil and po420 went out.I stell have po430 code.My car is like yours it runing as good as it ever has.You would think if catalytic converter was bad your temp.would go up.Ichanged to Mobil EP 5-30 motor oil and my temp.is lower than its every been.I allso use Balwin oil & air filter I think they are the best made.As long as my car keeps running this great at 128000 miles Iam going to leave it.Let me know if you fine the problem for po430 code it could be 02 sensor.Thanks carl59@verizon.net

[maine_maxima]

I got the 0420 code when I brought my maxima to VIP. They said more than likely it is the cat and it would be worth it to spend $75 for an hour of labor to let them take a look.

It's a 2000 maxima with 81,000 on it. He also told me its just out of warranty (<80K) which was even better news. I've noticed some weird noises when giving it full acceleration and seems to delay before really putting the power to the wheels, but besides that, nothing really physically wrong with it.

Cheaper to let a local guy do it, or these guys? Whats the most common problem with the 0420 code?

Thanks

[NissanTech]

Cheaper to let a local guy do it, or these guys?

Probably your local mechanic. They don't have the overhead that the dealer does.

Whats the most common problem with the 0420 code?

There is a bulletin for that problem. Go to the 2000 maxima bulletin list: http://x.nissanhelp.com/forums/Knowledgebase/links/215

Keyword Filter: "p0420"

The bulletin recommends to check the engine control unit program number, and if the ECM already has the latest program you have to replaced the O2 sensors and cat.

[moshiachnow]

We have had a history of getting the check engine light and an 0420 code. We took the car into the dealer, they charged us $95 and said that the ECM needed reprogramming. (We argued that we should not have to pay if it is a defect in the car and if there is a bulletin on it. Eventually - two months later - the dealer begrudgingly gave us a refund, after being contacted by Nissan's main offices).

So, the light went back on a day after they reprogrammed the ECM. It went off by itself a few weeks later. Now it is back on. I see that there is a voluntary recall for problems with a sensor that requires reprogramming the ECM. I also see that there is a service bulletin pointing out that sometimes the ECM will give an 0420 code, even though there is nothing wrong with the catalytic converter.

My question is, if we take the car in for the recall issue, we should not get charged for it, correct? The dealer says that they will charge $95 to inspect the car. I don't want to have to get involved with this headache again. Would some knowledgeable tech let me know what the proper response of an ethical dealer would be in this situation?

Thanks.

[mpe235]

Originally Posted by moshiachnow

We have had a history of getting the check engine light and an 0420 code. We took the car into the dealer, they charged us $95 and said that the ECM needed reprogramming. (We argued that we should not have to pay if it is a defect in the car and if there is a bulletin on it. Eventually - two months later - the dealer begrudgingly gave us a refund, after being contacted by Nissan's main offices).

So, the light went back on a day after they reprogrammed the ECM. It went off by itself a few weeks later. Now it is back on. I see that there is a voluntary recall for problems with a sensor that requires reprogramming the ECM. I also see that there is a service bulletin pointing out that sometimes the ECM will give an 0420 code, even though there is nothing wrong with the catalytic converter.

My question is, if we take the car in for the recall issue, we should not get charged for it, correct? The dealer says that they will charge $95 to inspect the car. I don't want to have to get involved with this headache again. Would some knowledgeable tech let me know what the proper response of an ethical dealer would be in this situation?
Thanks.

How many miles are on the car? Usually when these cars give you a p0420 code they do need a catalytic convertor. It is a simple check with the nissan scan tool to check the o2 sensor readings to determine if the cat. is working. It is covered for 8 years or 80,000 miles. The recalls apply only to specific vin #'s so if they run your car through nissans computer and it doesn't show an open recall they can't do it and get paid by nissan for it. The proper response of an ethical dealer would be to check the code for free to see if is indeed a p0420 code. If it is they should repair it under the 8/80 warranty. If not they should stop there and ask you to approve the diag charge for whatever code they found. Keep in mind that there are several reasons why the light can come on. There is a possibility that it is not related to the previous repair.

[moshiachnow]

It has about 42,000 miles. It looks like the way we will do it is first take the car in for the voluntary recall for reprogramming the ECM (NTB07-081). Then we will see if that stops the check engine light from going on. If it still goes on, then we ask them to follow the service bulletin procedure for the 0420 error code and check the catalytic converter. If it is the converter, then the whole thing should be under warranty. If the converter looks OK, then the service bulletin says that the dealer should reprogram the ECM. Apparently the ECM on this model has been giving erroneous code 0420's even when the catalytic converter is OK.

The question is about that reprogramming - should the dealer charge to reprogram the ECM, if he does it after checking the converter and finding the converter to be OK? Is that a warrantied service?

TIA.

[mpe235]

Ecm reprogramming is also covered for 8 years 80,000 miles.

[AZMaxima53]

I've been having an intermittent 0420 code. My regular mechanic thinks it's the cat, the dealer wants to check it first, as they think it might not be. The guy on JustAnswer says the same thing. Worst thing about this is my 2001 has 114,000 miles on it. No warranty, so I want to be SURE what is happening!

[sergey85]

OBD-II Trouble Code: P0420 Catalyst System Efficiency Below Threshold (Bank 1) have a look at this site my fathers honda had the same code but was reset and never came back. i would try to see if u can clear the code and see if it comes back. it could be a few things u can check as u see on the site.

[AZMaxima53]

Dealer says I need both cats replaced as one (or more) of the fuel injectors are restricted and dumping raw fuel into the cats... Mechanic who looked at it first saw NO evidence of fuel injector problem (although they said the cats were bad, too). Car doesn't get as good a mileage as my 97 Maxima did, but it's not so bad that I would know there was something wrong. Car runs fine, passed emissions AFTER the light started coming on. Whatever needs to be done, the dealer won't be doing it. ECM has evidently already been reprogrammed by prior owner.

Grrrr....

[sergey85]

their is only one cat on that year the newer 04+ maximas have two(cause they have dual exhausts).well if u need the cat replaced look around and see a good one maybe even get a fast cat.