Help with CEL P0136 on '02 Forester?

[mparkes]

On my 2002 Forester, the CEL has been staying on, took it to Autozone
they read out a P0136 error code, which is suppossedly a Rear Oxygen
Sensor Circuit Malfunction - how difficult are these to replace? I'd
like to save a few bux and do it myself if possible. I have also read
some posts that seem to indicate the wiring to these sensors will
sometimes go bad, throwing the error code. thanks for any help!

 

[Carl 1 Lucky Texan]

On my 2002 Forester, the CEL has been staying on, took it to Autozone
they read out a P0136 error code, which is suppossedly a Rear Oxygen
Sensor Circuit Malfunction - how difficult are these to replace? I'd
like to save a few bux and do it myself if possible. I have also read
some posts that seem to indicate the wiring to these sensors will
sometimes go bad, throwing the error code. thanks for any help!

Did they clear the CEL and, if so, did it come back on very quickly?


Carl

 

[mparkes]

They cleared it earlier today and it hasn't come back on yet.

 

[Carl 1 Lucky Texan]

They cleared it earlier today and it hasn't come back on yet.

I would wait to see if it returns. A cut wire might return immediately,
a slow or 'lazy sensor' might come back in a few weeks. It MAY not come
back at all. Usually, as for wear, the front sensor goes first - more
heat and un-'catalyzed' combustion products hit it first. How many miles
on your car?

Carl

 

[mparkes]

Carl, 100,000 miles -

So this is the rear sensor ...after the catalytic conv? - the guy at
Autozone said it was the sensor before the CC. But the error code
indicates Bank I Sensor 2... so it sounds like its definately AFTER the
CC. Maybe I'll just wait and see if it comes back.
The CEL has been coming on occasionally lately but then would go off by
itself. Not sure if this is all connected. I thought perhaps the gas
cap wasn't sealing as it didn't seem to be pressurizing the tank
lately. No "woosh" of escaping air when you open the cap.

 

[Carl 1 Lucky Texan]

Carl, 100,000 miles -

So this is the rear sensor ...after the catalytic conv? - the guy at
Autozone said it was the sensor before the CC. But the error code
indicates Bank I Sensor 2... so it sounds like its definately AFTER the
CC. Maybe I'll just wait and see if it comes back.
The CEL has been coming on occasionally lately but then would go off by
itself. Not sure if this is all connected. I thought perhaps the gas
cap wasn't sealing as it didn't seem to be pressurizing the tank
lately. No "woosh" of escaping air when you open the cap.

All 4 cylinders will show as 'bank one' (1/2 V8) even if they are not
inline. Your car MAY have 3 sensors - anyone? - anyways, I's be very
tempted to confirm which sensor if possible - sounds like it is getting
'lazy' - you can actually see them 'switch' on an o'scope and maybe some
analog voltmeters - google 'lamda sensor' or 'oxygen sensor' . Do not
use a voltmeter on them! It is either useless or damaging IIRC.

you might post the code and conditions at www.usmb.net for more input,
but I think you are just getting to point of needing a sensor. Just need
to confirm which one. The AZ guy probably got the correct code number -
but it may mean something 'slightly' different depending on the year
model,etc.

just my $0.02


Carl