Hello,

I have a 2000 SE with 5 Speed, Fed Spec, Stillen Intake and Y-pipe, and it's been running like crap lately, and the CEL came on.

I just took my max to Autozone and they read the P0420 "Catalyst Efficency Below Threshold (Bank One)" code. What do I need to do to fix this?

Thanks for the help in advance!!!

 

I'd try a new 02-sensor.

How many miles?

 

That's the one behind the main cat.

Otherwise, it could be:
1)a bad main cat<~~doubt it.
2)exhaust tube<~~leaky y-pipe/flange
3)intake air leak<~~stillen intake
4)injectors
5)injector leak
6)spark plug<~~depends on mileage
7)improper ignition timing<~~doubt it.

...per the FSM.

I'd do the 02-sensor and plugs to see if that's it.

 

Thanks for the quick response....

It's got 74K miles...I already replaced the ignition coils and I replaced the O2 sensor closest to the front of the car. I just did the spark plugs and ran some BG44K in it about 10K ago and that didn't help anything.

Sounds like I should order the O2 sensor and maybe check the Y-pipe bolts for tightness.

Bank one is after the Cat? That doesn't really make sense, but you definitely know your $hit so I'll order one. Do you know the part #? Do you have any idea where I could get the best price on one?

 

It's possible it's a bad downstream O2 sensor, but since your car is running like crap that's probably not it. Downstream sensors are only used by the ECU to monitor the catalyst system and if one fails it will set off the light but won't affect drivability. The fact that you're having drivability problems indicates that something else is wrong besides a bad O2 sensor.

 

The 2 biggest problems I've noticed are that until it warms up it will stutter violently while accelerating between 1500 and 2000 RPM.

Also, when it's at a stop, if I try to hold the RPM constant in that same range, the RPM's will bounce down repeatedly on a regular (1-2 sec) interval.

Does that help with the diagnosis?

 

That was 02 sensor 1 on bank 2.

Bank 1 is the rear bank closest to the firewall, it could be the first or second 02 though. By the description it sounds like the cat is not registering properly on bank 1, so either 02 could be malfunctioning.

Autozone is probably WAY cheaper then a OEM one from Nissan. On my other Nissan it was $30 vs. $1XX.

 

I had SES light on ( same code PO420) for a month or something and few days ago after i changed oil and air filter just next morning went SES light off....weird....

 

So a 2K fed-spec has a total of 4 oxygen sensors? (2 before the cat, 2 after?)

 

No, fed = 3, cali = 4.

 

I seem to remember there being 2 before the cat (bank 2) and 1 after the cat (bank 1) on mine...is this correct?

 

You're all wrong.
Go back to the dealer. You're covered for this TSB for P0420/P0430 on 00 and 01 A33 up to 80K mi. NO CHARGE, FREE, etc.
I just had the TSB applied to Toylet902's car on Wednesday.
30 minute reprogram. If the Oxygen sensors are 'slow' to react, or don't cycle, there are HO2S codes that will pop up.

 

YEP. this an ECU problem and nothing else.

please, everyone... there is a TSB out for this... check the nissanusa.com site. Your car needs an ECU update at the dealer under the 80k emission warranty.

I don't know if I still have a copy of the work order done, but PM me and i'll see if i can find it for you.

 

The only TSB I've seen for this says "all 2000-2001 (A33) - except 2000 Fed-spec emissions" (NTB00-070a)

 

I've been doing some research on this here and I think the problem I am having is this "bucking/surging" problem.

http://forums.maxima.org/showthread.php?t=267367

It looks like people are replacing their MAF sensor to fix this? Does that really work???

I don't think that will solve my P0420 problem though, will it? It sounds like I might have 2 seperate problems.

 

I don't have a FED spec, so you may be correct.

Mine(cali) has one before and one after each precat and none after the main cat.

 

I just had this problem and had it resolved FREE by nissan under the 80/80 warranty!

First, they flashed my ECU, and when that didn't work, they replaced my main cat.

All free, no problems since.....take it to a dealer!!


das

 

What TSB did you reference??? Do you have a fed or cali-spec?

 

Hawk,

I didn't have to reference a TSB at my dealer, they are well aware of emission codes and related problems...hopefully yours is as well.

I have a cali spec.....

das

 

The reason I ask is that there is a TSB out there for the P0420 problem, but it doesn't apply to 2000 Fed Spec Maximas. Man this is confusing.

 

have you tried taking it to the dealer?

 

I pulled the same code on my 2K SE, took it to stealership and they flashed the ECU. Problem/Light never came back this was about 15K miles ago!

 

Does anybody know the TSB number? I am in Boston area and just got the MIL light on 2000 5-spd. The car had 59910 miles on it when it came out in the middle of the drive. I could detect no other symptoms.

If anybody could look up their service receipt, there might be the TSB number listed on it. It will help me tremendously as I don't know if my dealer will voluteer the TSB without providing proof.

Thanks,
- Vikas

 

sounds like you have 2 problems the code is not going to make your car run bad it sounds like you need to cheak your mass air for leaks or see if it is bad

 

If you have a California emissions Max and the code is P0420 (I'm assuming you've had the code pulled at AutoZone or elsewhere) then THIS TSB applies. Don't worry...you still have 20K miles before it runs out if the code was indeed P0420. Otherwise, chances are it was probably for something only covered for 3/36 anyway.

 

What do I do with my FED-SPEC maxima that has the P0420 code???

 

Well, if you look at the TSB flowchart it says: Check Emissions Certifiication Label, underside of engine hood {see Figure 1, pg. 3}. Certified for California emissions? [If not] Bulletin does not apply. Use Service Manual DTC P0420 Procedure.

I don't have a factory service manual, but I'm sure someone on this forum does. But the long and short of it is the problem won't be solved by simply reflashing the ECU. You may actually have a bad catalytic converter, and if so, it's covered for 8/80 as well. Can't remember, have you taken your car to the dealer? If so, what did they say the problem was? If not, they'll charge you a diagnostic fee ($85 or so), but if it's a covered item, you'll get the fee back.

 

Well, at least in my case it was P0420. I had Autozone clear the code.

My car had the ECM reprogrammed for this exact problem 3 years ago. My service record (Oct, 2001) says "DE98AA Reprogram ECP for DTC P0420) The part number mentioned is 237103Y101At that time I had about 28K miles on the clock. The light came out of nowhere with no other symptoms.

Looking at the TSB provided by DanL, that was indeed performed on this car.

I need to look at the emission lable to find out if my car is Fed or Cal certified. At least the ECP P/N matches with what is listed on the TSB. I wonder if the part listed is the old or the new one.

After reset on P0420, how long before the MIL starts coming on again?

Thanks,
- Vikas

 

You could do what I do - ignore it.

First, you have a y-pipe that eliminated the pre-cats. I would be careful about taking it to a dealer and complaining about an emissions code - they are likely to tell you to take a walk (although they may not)

Second, as I understand the problem, the pre-cats are small cats that take care of emissions before the main cat heats up. If you have a fed - spec with an 02 sensor before and after the main cat, and have removed the pre-cats, the 02 sensor before and the 02 sensor after the main cat can have reading differences at times that are not within a pre-determined range thus triggering the 420 code.

My 420 code comes and goes.

 

I think this is the way to go. I originally thought my drivability problem might have been related to the P0420, but it sounds like that is related to the MAF, and I have ordered a new one of those. Anyone know how to get those star-head screws with a peg in the middle out? I'm guessing it takes a special tool??

I haven't taken it to the dealer yet because I don't want to be told to "take a hike" when I go in complaining about an emissions problem and I have the y-pipe on there. I know they have to prove that the mod caused the problem, but it's probably not worth the fight.

 

dude, its more than just your O2 sensor, because the sensors behind the cat are not performance related. Since you said your car is running like crap, there is a good chance its your MAF.

 

Well, I reset the ECU for the P0420 and it hasn't come back yet, so that's good. Probably just something I'll have to live with.

And for the drivability issues.....FIXED!!! I got a MAF from southpoint Nissan ($90 shipped) and it made the car feel like new again. Nice smooth acceleration all the way up to the redline. The jerking/bucking/surging and power loss are gone!! It really is a night and day difference. Thanks for all the help everyone!!

Also, FYI, there is a difference between the old and new MAF. The old one only had 4 connectors on it, the new one has 5, and the new one has a green dot on it, similar to the gray dots that come on the updated ignition coils.

I'm definitely glad that the max is running well again, but I am truly disappointed in Nissan. This is the 3rd part on my car (O2 sensor, ignition coils, MAF) that I have had to replace at my own expense since my warranty expired, where Nissan has issued an updated part due to the originals being defective. I know it's just the car business, but it does **** me off when they are admitting that their parts are defective, yet they don't recall or offer to replace them.

Just my 2c. But it is sure nice to have the old Maxima back again.

 

Yeah..

My car has that damn code..


I wasn't aware of the TSB but I'm over 80k miles anyways, what can I do???

how much will they rape me for if i bring the car in?


i just ignore it but it sucks because when something does go wrong it throws a code, you will not be aware of it..

 

In my case, the TSB did not apply since I have a 2K Fed-Spec. It only applies to Cali spec Maximas. But from what I've heard and my experience, is that the P0420 code is just a computer bug, and won't affect driveability at all. I thought the P0420 might be related to the car running like crap, but it wasn't. It was all the MAF. I just unhooked the battery for a couple hours and the code went away.

As far as I know, when your CEL is on and something else goes wrong with the car, it will flash a few times to let you know another code has been stored. I've seen mine flash a few times.

 

I guess the doc knows best if your codes have been reset then drive it and see if thay come back thay might not

 

thanks.

My car is Cali spec and i just had the CEL checked today.. it was the same code that it has had for a while.

i didn't know about it flashing, i'm used to my 4th gen.

 

Guess what; another 400 miles on the clock and the CEL is back again :-( It is the same 0420 code. I have erased it. I suspect it will be back again and then I will have to visit the dealer and plead to get the TSB applied.

If I understand correctly, the TSB involves re-programming the threshold for that code. However, I would like to know what it is trying to measure and why it is getting out of acceptable range.

Otherwise, all the TSB is doing is delaying the eventual replacement of "the" slowly dying part when the vehicle is past the "covered" 80K miles.

Am I making any sense here? Are there other topics which discusses Code P0420?

Thanks,

- Vikas

 

P0420 is caused by either 2 things:
1. the computer "bug" that needs updating.
2. a bad catalytic converter

i had the first done and the light came back. they tested the catalytic converter and it failed, meaning it was bad. they quoted me $1000. i bought a Random Technology Cat for $198 shipped and the light is gone.

 

The P0420 light keeps on coming and I keep on resetting it (almost every week after few hundred miles). Unfortunatelly, the car just fllunked the emission because it was "Not Ready". I had recently cleared the code. I am afraid that I am not going to get a successful test completed stored before getting to the emission station to get the sticker :-(

Can somebody provide me a pointer which can confirm that the dealer has to cover code P0420 up to 80K miles? Mine now has 65K on it.

Does anybody know how many drive cycles does ECU need after clearing the code until the tests are passed? My research shows that this information is highly guarded secret :-(

Thanks,
- Vikas

 

Lucky us in Qc -Canada we dont have to pass emission. I have had the PO420 on for a while ( 6 months or so ), I changed 2 x O2 sensor and erase the code but it kept coming back until the CEL went off by itself few days ago, so I dunno but the car is running fine.

Cheers

AA