I have a 96 Max with over 285k miles. I have never really had many
issues with it beyond the usual maintenance and wear and tear.
However, for the last 3 years, almost all of my emission sensors have
been replaced. I thought I was through with all that for another
200k
when my "Check Engine" light just recently came back on. It was
0503,
the RH Heated O2 Sensor.

I purchased the normally $80 part online for about $50. It was an
SNG
sensor. I replaced it, reset the computer and drove. I also
replaced
my fuel filter and added a short-ram intake kit all on the same day.
Almost a week later, the light came back on. It was the same code.
I
cleared it, and it came back on the within miles.

I have reset it a few times. Since all of this, my car has been
getting less MPG, from about 27MPG to 18. Moreover, it has now
started to hesitate when I am accelerating from a stop or from less
than 20mph. It is almost acting as if it is not getting gas or
something.

It drives fine on at highway speeds. It accelerates a little faster
to 60, 70, 80 and so on. In addition, I have been able to drive at
80, 90 and even 100 without the car going over 3,000RPM. I attribute
that to the air filter mod, but I could be wrong.

Therefore, Nissan community, what do you think the problem is? Is my
new O2 sensor bad? If I had bought it locally, would you have
suggested I returned it already? On the other hand, is it the mod or
something else?

* I will let you all know that I am no expert but I have done most of
the work on my car (CV axle replacement, radiator and such), so I am
no slouch. However, I am lost on what I should do next.

Have you replaced the knock sensor? It will not throw a code by and in and
of itself, however it will give you BAD gas mileage, if bad. What about
plugs? changed them lately? I just put a new knock sensor on mine (about
200K miles) and replaced the plugs, it got rid of allot of seemingly
unrelated codes.
Just a thought, but with that many miles you DEFIANTLY need to replace your
knock sensor at a minimum.
Bitsbucket
(Oh and I have 2, 4th gen Maximas, a 96 and a 97 and have done most of the
maintenance myself too)
"Charlie 3" <JustCS3 (AT) gmail (DOT) com> wrote

Oh, and knock sensor from dealer is VERY expensive, however there is a guy
on ebay that sells them for around 60 bucks, they are almost 3 times that
from the dealer, if not more, depending on who you buy it from. I got mine
from ebay and it really increased my mileage....

"Bitsbucket" <none (AT) none (DOT) com> wrote

On Mar 7, 2:49 pm, "Bitsbucket" <n... (AT) none (DOT) com> wrote:
Thank you for your response. I had the knock, post-cat and another
sensor changed about a year or so ago. I had changed the LH O2 sensor
before that. I purchased a BOSCH sensor from AutoZone today. I went
ahead and did that so I could return the SNG from the Net. The BOSCH
is $40 more.

I was asked about changing the plugs as well by the AZ salesman. I
had thought about that but I have also noticed irratic timing, the car
either idles normal or a little below 1000. Also, the gas consumption
is irratic. It seems normal since my last fill-up. But it was a
drinking it up before that.

At the very least, I will have a new sensor by a company I trust. I
think if the code didn't take a week to come back initially, I would
have moved on to something else.