Service Engine Light and Self Dimming Lights

[Heath Vogt]

OK.   So my wife's '98 Sentra SE with 45,000 miles
studders a little at 4,500rpm plus or minus 500 rpm.
I change plugs, plug wires, distributor cap and rotor.
 Still the same issue.  So I break down and dump the
money on 02 sensors.  The cat sensor is an absolute
PITA to get off - ended up cutting it off at the nut
and welding a bar on to get leverage after stripping
it out with the correct socket (it was not a good
time).  Now, before I completely destroyed the sensor,
I started the car with the sensor disconnected to make
sure it would still run, just in case I still couldn't
get it off.   After a day and a half of soaking and
hitting and heating, I finally got it off.  I put in
the new one (with anti-seize - came with it right on
the threads), and the car still exibited the same
behavior, and the check engine light was on.  I
figured with running it with out the O2 hooked up I
probably just created an error code and needed to
reset the computer.  So I unhooked the battery around
7 or so last night and hooked it back up around 6 this
morning.  The service engine light is still on.  I
drove it in this mornging and didn't notice it
hesitating any more, but the light is still on.   What
do I do short of taking it to the dealer?

The other oddity I noticed on the way into work, and
perhaps it's always been this way and I've just not
noticed because I don't normally steal my wife's car,
is at about 6,000rpm the headlights dim.  I thought I
was just having a stroke at first so wasn't that
worried, but I rev'd it up a couple of times and sure
enough, the headlights dim every time.  What's up with
that?  Does the Alt. switch off at a certain RPM to
keep from overcharging or something?

Anyway - any help on the service engine soon light and
and explanation of the lights would be greatly
apreciated.  Hopefully I gave all the details without
being too lengthy.

Heath

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Heath Vogt BSME
'69 Baja Bug - Brutus "the wonder bug"
'01 Isuzu Trooper
'98 Nissan Sentra SE