P0420 and NTB00-070a?

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davejohansen@gmail.com - 29 Nov 2007 16:29 GMT

I have a 2001 Maxima with about 95,000 miles on it. A few months ago
the check engine light started turning on for about a day or so at
random intervals. Every time the code was P0420, and after doing a
little searching I found out that TSB #NTB00-070a will supposedly fix
this problem.

So I took my vehicle to the Jim Click Nissan Dealer here in Tucson
(first time I've ever been there) and they told me that the O2 Sensor,
front pipe, and Catalytic Converter needed to be replaced (which would
cost $1400). I told them to not do anything yet.

I did a little more searching and found the actual TSB document and it
says that the first and only diagnostic that they should have done is
to check the ECM Part Number to see if it is faulty. The TSB document
says that the ECM P/N can be found on the Consult-II self-diagnostic
print out, but is there some way that I can find the ECM Part Number
myself to see if they're just trying to rip me off?

Thanks,
Dave

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Charles G. Hill - 30 Nov 2007 01:37 GMT

For lo, Dave Johansen hath proclaimed:

> I have a 2001 Maxima with about 95,000 miles on it. A few months ago
> the check engine light started turning on for about a day or so at
> random intervals. Every time the code was P0420, and after doing a
> little searching I found out that TSB #NTB00-070a will supposedly fix
> this problem.

On the Infiniti I30, the pertinent TSB is ITB00-054b. (ITB00-054a
has been superseded; perhaps there's a b version for the Maxima.)

> (first time I've ever been there) and they told me that the O2 Sensor,
> front pipe, and Catalytic Converter needed to be replaced (which would
> cost $1400). I told them to not do anything yet.

What I was told (and what I verified at Alldata's pay side) was
that only the front pipe and an O2 sensor require replacement.
This could be the difference between a and b TSBs, maybe.

> I did a little more searching and found the actual TSB document and it
> says that the first and only diagnostic that they should have done is
> to check the ECM Part Number to see if it is faulty. The TSB document
> says that the ECM P/N can be found on the Consult-II self-diagnostic
> print out, but is there some way that I can find the ECM Part Number
> myself to see if they're just trying to rip me off?

That I couldn't tell you. The Infiniti service guy told me that
the first thing they're supposed to do is check that part number,
and if it's not up to the current release, to immediately update
the ECM. If it's a current number (as mine, alas, was), you get
to replace hardware.

I should point out here that the front pipe and the O2 sensor cost
just about as much as a cat.

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jcearly63@gmail.com - 28 Jan 2008 13:55 GMT

On Nov 29 2007, 11:29 am, "davejohan...@gmail.com"
<davejohan...@gmail.com> wrote:

> I have a 2001 Maxima with about 95,000 miles on it. A few months ago
> the check engine light started turning on for about a day or so at
[quoted text clipped - 16 lines]
> Thanks,
> Dave

Dave,
I too have a 2001 Maxima SE with 105K miles. I was having P0171 which
led me to replace the MAF Sensor. After resetting the codes, I'm now
getting P0420. Did you ever get your issue resolved? What was your
final solution?

Thanks,
GolfGuru

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davejohansen@gmail.com - 28 Jan 2008 17:05 GMT

On Jan 28, 6:55 am, jcearl...@gmail.com wrote:

> On Nov 29 2007, 11:29 am, "davejohan...@gmail.com"
>
[quoted text clipped - 28 lines]
> Thanks,
> GolfGuru

Here's my full story:

A while ago (about 1.5-2 years ago) I had the P0171 code too and I
replaced the MAF Sensor, which fixed that problem. Then several months
later (can't remember exactly how long), the code P0420 started
popping up intermittently. I got lucky and it was off when I went to
get my emissions test, but I finally decided to go and get it checked
out.

I took my car to the Nissan dealer to have the ECU reprogrammed for
the new MAF Sensor (something that we recommended in the instructions
that came with the sensor), and I asked about the code P0420 and the
associated TSB. They said that the TSB did not apply to my car (I
guess it's only certain ECUs or something), and that I would need to
have the front O2 Sensor, pipe, and catalytic converter changed in
order to fix the problem (which would cost $1400). I told them to hold
off on doing that, because I can probably do the O2 Sensor myself and
I can probably have a muffler shop change the cat for a LOT less.

But anyway, the ECU reprogram for the new MSF Sensor seems to have
changed something, because now the check engine light is on all the
time (which further backs up the fact that the TSB doesn't apply to
me).

I don't know if any of this info helped, but let me know if you have
any other questions.

Dave

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