CEL on '96 Impreza

[Christian Davenport]

I have a '96 Impreza Outback Sport with the 2.2L motor and 123k miles.
Recently, the check engine light will come on and stay on for a few
days, and then go out for a few days, and then come back on for a few
days, etc., etc.....

It hasn't bothered me too much because when the light is on, the
engine seems to run fine - starts OK, idles OK, accelerates OK, not
rough, etc., except for fuel consumption. The mileage goes way down.
I can actually notice a drop on the fuel guage in my 7-mile commute.
When the CEL is off, mileage returns to normal.

I'm going to take a shot at the possible problem, and I'd like to get
others' opinions.

I'm guessing it's either: 1. A bad oxygen sensor (they have never
been replaced) or, 2. MAF has gone bad. My reasoning for this comes
from what I know of the engine computer and how it is programmed with
a "limp home" mode when something goes wrong. Considering that my two
possible culprits are both "input" devices to calculate the fuel/air
ratio by the engine computer, when the CEL is lit, is the computer in
a "limp" mode, possibly using a default, overly-rich fuel/air mixture
as to keep things from getting too hot, thus the high fuel
consumption?

It's just a guess.

Thanks,
Christian

 

[CompUser]

I have a '96 Impreza Outback Sport with the 2.2L motor and 123k miles.
Recently, the check engine light will come on and stay on for a few

I'm guessing it's either: 1. A bad oxygen sensor (they have never
been replaced) or, 2. MAF has gone bad.

Are you in USA? Find an Autozone store near ya
and they'll read your codes for free:

http://www1.autozone.com/servlet/UiBroker?
UseCase=ST001&UserAction=displayStoreLocator

Then pop over to:

http://www.troublecodes.net/Subaru/

....and hopefully your codes will show...mine,
P1491, doesn't...off to see dealer tomorrow!

Steve
04 WRX

 

[David]

I'm guessing it's either: 1. A bad oxygen sensor (they have never
been replaced)

At that mileage, it's reasonable to replace the O2 Sensor(s) even if they're
still OK.

This link (that I think I learned here today) shows how to retrieve your
trouble codes from the CEL (no scanner required):
http://www.troublecodes.net/Subaru/

More trouble code stuff here:
http://www.obdii.com/codes.html

If it's running with an overly rich fuel mixture, it can lead to other problems,
which I think include fouling your O2 sensors. Dunno if it can damage your
cat, but it's likely the original problem can: at least some cars only light up
the CEL for trouble codes that can damage the emission system. Others
go unreported unless you scan. Dunno if Subaru works that way.

 

[Nicolas Bernard]

hI !

Maybe it could be the cam sensor . I had this problem on my old car bye!

 

[George]

It sounds like your gas tank sending unit is failing. What happens is the
slider get a bad spot so the fuel gauge drops. The CEL comes on. Then after
about 200 miles it clears. You fill the tank and when the slider gets to the
bad spot. cycle repeats.

Subaru get big money for new sending units. On the Outback there at 2 units.
The pair costs like $400. I have heard you can fix the unit.