O2 Code and possible causes

[.._..]

Took my OBW 2001 72k in for oil and coolant change because the coolant was a
bit low and looked grubby to me. This gives a known starting point to look
for more cross contamination that might be a leaking head gasket.

In the weeks prior, had the CEL light come on a few times (then going off
after a few stop start cycles) and assumed it was the gas cap thing as it
always went away when I filled up or tightened the cap. (I only found it
loose once.)

The CEL was on when I went in for the other work and I had them pull the
codes.

Here's what it had in it (recent at top):

P0136 O2 Sensor Circuit Range/Performance Problem - Malfunction (Bank 1
Sensor 2)

P0500 Vehicle Speed Sensor Malfunction

P0512 Starter switch circuit high input

P0151 O2 Sensor Circuit Range/Performance Problem - Low Input (Bank 2
Sensor 1)

P0154 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)

They imediately went to "we don't have that part if you come back on Tuesday
we can do the swap for $250" I delayed that as it would be sort of useless
in the face of a 3k bill for the gasket (would probably junk the car if
that's what the problem is).

Having gone through the O2 sensor BS before, it does not seem the same to
me. For one, last time there was no CEL at all, but all sorts of engine
power or hesitation issues. Given the fact the O2 sensor has a pretty
integral part to play, I am leery of just replacing it. I think it is the
same one as replaced last time, so it's only 3 years old.

So I am curious as to if anybody has suggestions of other stuff the codes
could represent other than the O2 sensor. The ODB2 code set seems to imply
there is two "bank 2" sensors, so this could be the other one failing, but
those codes are shared amongst many models so there could be one in front.

So...

What else could this be?

How many sensors are there (up front)?

Is $250 a high price? ($100 part, rest labor)

 

[Todd H.]

Took my OBW 2001 72k in for oil and coolant change because the coolant was a
bit low

Do this at a dealer? If not, get thee to a dealer and report to them
that you have experienced coolant loss and ask them to do a test for
head gasket leakage. There's a dye test for it--takes a few hours.

In the weeks prior, had the CEL light come on a few times (then going off
after a few stop start cycles) and assumed it was the gas cap thing as it
always went away when I filled up or tightened the cap. (I only found it
loose once.)

The CEL was on when I went in for the other work and I had them pull the
codes.

Here's what it had in it (recent at top):

P0136 O2 Sensor Circuit Range/Performance Problem - Malfunction (Bank 1
Sensor 2)

P0500 Vehicle Speed Sensor Malfunction

P0512 Starter switch circuit high input

P0151 O2 Sensor Circuit Range/Performance Problem - Low Input (Bank 2
Sensor 1)

P0154 O2 Sensor Circuit No Activity Detected (Bank 2 Sensor 1)

They imediately went to "we don't have that part if you come back on Tuesday
we can do the swap for $250" I delayed that as it would be sort of useless
in the face of a 3k bill for the gasket (would probably junk the car if
that's what the problem is).

A few data points:
You're under 100k -- get to a Subie dealer. Head gasket job
will be on them, I'm guessin.

I had my headgasket replaced and both heads rebuilt along with
a catalytic converter replaced for $1800. That was a bit of a
gift from the tech I used, but $2400 is probably more in
line. Sutract the cat and it's more around $2k if you can
find a good independent.


I'll defer on your other questions due to lack of 02 sensor problems.

But, do call Subaru customer server and open a case on your coolant
loss issue. 1-800-Subaru3.

Get to a dealer asap, indicate that you've opened a case on your
coolant use issue, and report that when your coolant was recently
changed, you noted that a lot of coolant had been used and the
overflow bottle looked dirty as well, that you're aware of the rampant
2.5L head gasket issues and would very much like a diagnostic done for
head gasket leakage.

The dealer will report the diagnostic results to Subaru, they'll
decide how much they'll pay (likely all of it, given your mileage).
The dealer should be happy to do the work and bill subaru.

Provided of course, you acted on the coolant conditioner recall
promptly....

Enjoy the sinking feeling that is this blog:
http://scott.mcgerik.com/2004/02/18/subaru-outback-head-gasket-leak/


Best Regards,