99 impreza check engine light

Engine light comes on for a day or so then off now on again
how do i get the code to see what is failing
car has 74,000 miles
is auto with 2.2 (wagon)
:banghead:

Auto Zone will pull your code(s) for free. Even when the light goes back off, the code should be stored.

Let us know what they are.

ok will get it checked at some point and let everyone know
still off at this point and don't have time to work on now
Did run a can of seafoam thru tank may help
Don

ok had Parts America pull code can't deal with AutoZone
P0325 knock Sensor1
circuit malfunction Bank1 or 1 Sensor
guess this is the up stream heated oxygen sensor
Don

Found on another forum:
i would suggest just taking it out, cleaning the bottom contact, and checking the wire harness first. could just be a bit loose, too tight, dirty or something. (well you hope anyway).

The knock sensor is a piezoelectric microphone that is situated on the top of the engine block, approximately seven inches below the bare throttle cable near the back of the intake manifold. It is black in color and shaped like a stack of eight, 3/8 inch size, flat washers. That is to say that it is a doughnut shaped piece, the diameter of a quarter. It is bolted to the engine with one, vertically situated, eight millimeter bolt that is about 40 millimeters long which accepts a 12 mm socket wrench. It has one wire that plugs into a wiring harness just below the throttle cable.

should be torqued to about 17lbs, which isnt much!
I think the knock sensor is about a $100 part from Subaru, and many people report it takes about 5 minutes to change it out. Be carefull not to over-torque the bolt.

Found more info about the knock sensor on scoobymods here:
http://www.scoobymods.com/forums/showthread.php?t=4039

ok took it out cleanded up contacts on bottom and put it back in
that didn't work after 3 days light came back on
strange thing about it is that the check engine light comes on while starting the engine not when it is running
must just be a bad sensor
will order a new one in a few days and change it
it is easy to change it is located under the throttle cable just behind the fi
system just to the driver side on my 2.2 engine
Don

strange thing about it is that the check engine light comes on while starting the engine not when it is running
"Starting" as in cranking to start, or during engine warm-up?

My check engine light comes on when I start my car, so does the oil light, the battery light, the seatbelt light....all part of the computer system check when you start the car.

Like Jay asked, is it when you start the car only or when it's still warming up.

yes when it is running
when i start car it is and stays on
what I was saying is that it never comes on when I am driving when it might start knocking it comes on when car starts and stays on
just not every time

update changed the knock sensor last week so will see if it takes care of it
on the 2.2 the sensor is right under the throtle cable easy to get to and change
Don

try cleaning the plug then disconnect your battery and reconnect it to restart the computer.

Are you using the right octane of gas?

the knock sensor took care of the problem
and I run 87 gas always ran ok on it so no need to change
Don