My oxygen sensor in BANK 1 is bad according to the check engine code.

Where is this oxygen sensor on a 99' Forester???

Should be the forward O2 Sensor, mounted front on the forward catalytic convertor nearest the engine. On my outbacks, you can see part of it looking down from the passenger side in the engine bay. Not sure if the Foresters are configured differently but I wouldn't think so.

 

 

Edit:

 

Looks like on the forester, it is located on the up-pipe below the manifold, just before the front catalytic, though the text in the link states it is in the front CAT.

 

SubaruPartsForYou.com has a diagram here, not the greatest....

 

http://www.subarupartsforyou.com/cp_partdetail.php?partid=2346

 

Edit:

 

A better link and diagram (thanks to Nipper's find on this site)

 

http://opposedforces.com/parts/forester/us_s10/type_18/exhaust_system/exhaust/illustration_1/

Edited February 8, 200917 yr by PAezb

PAezb

 

Thanks for the Info.

My oxygen sensor in BANK 1 is bad according to the check engine code.

Where is this oxygen sensor on a 99' Forester???

'Bank 1' doesn't indicate whether it's the front or rear sensor, since on a 4 cylinder Subaru, there's only one bank. (It is more common for the front to fail, but not necessarily.) Also, there are oxygen sensor codes that can indicate problems with other than the sensor itself. What's the actual code (P013x or ...)?

Actually there are 2 banks of cylinders on the 4's as well. RH head is 1 and 3 and bank 1 and LH head is 2 and 4 and bank 2.

 

ON those cars there is only one set of catalyst pipes being shared so its the first sensor that you see closest to the engine.

 

On newer cars like the PZEV zero emissions cars, and 6 cyl cars (as early as the SVX) there are 2 sets of cats for each bank and such and this is what they were gearing up for with that description setup.

Actually there are 2 banks of cylinders on the 4's as well. RH head is 1 and 3 and bank 1 and LH head is 2 and 4 and bank 2.

Sorry, I didn't mean to oversimplify. Yes, there are obviously two cylinder banks on the fours, but since they share a single front (and rear) O2 sensor, any such code is for Bank 1 only -- a code for Bank 2 isn't generated.

 

My point was that the bank number isn't helpful in this case, the sensor number is what's important. A P0130 code, for example, would be for Bank 1, but so would P0135, even though one is for the front and one for the rear sensor.

Yep. Sorry to be stickler just want to be thorough.

Yep. Sorry to be stickler just want to be thorough.

 

slightly off topic, on a car with a transverse v6 engine, which side is bank 1, front or rear??

I have more info on my failing Oxygen sensor:

 

CODE: PO141

HEATED OXYGEN SENSOR BANK 1 SENSOR 2

 

Does this mean it is the second from the front sensor on the exhaust????

[...]CODE: PO141

HEATED OXYGEN SENSOR BANK 1 SENSOR 2

 

Does this mean it is the second from the front sensor on the exhaust????

It means it's the rear one, and specifically that there's a problem in its heater circuit. That could be caused by a failure of the heater inside the sensor itself, or just a poor (loose/corroded) connection.