Bank 1 Sensor 2 '01 Grd Cher o2 sensor location

mgrean · 02-04-2009, 02:13 PM

Hello-
My check engine light has been on for a while but recently my 01 Grand Cherokee (v6,4wd) started having idling problems after the car got warmed up. I took it to autozone to have the code read and I got PO138 and PO 141. 138 defines the problem as "H02S 12 circuit condition (heated oxygen sensor bank 1 sensor 2)" and the 141 definition is essentially identical. I picked up a new sensor today and when I got under the jeep I had no idea which sensor was bad. There is a dual exhaust so both sensors are right after mini catalytic converters, then the pipes join into the exhaust tube and head toward the rear. Is there anyway to figure out which is which or am I going have to trial and error?

Thanks, Mark

irishmarco · 02-04-2009, 09:37 PM

Guessing V8 here...bank 1 is the side cylinder 1 is on, just don't know off-hand on this motor. (sensor 2 is after-cat). I'll try a search and get back to you. Codes will need to be cleared after fix. Good idea to go ahead and soak threads with penetrating oil, not when hot!

gatorayde · 02-04-2009, 09:40 PM

You have the I6, not V6.

irishmarco · 02-04-2009, 10:07 PM

You could replace one sensor, disconnect battery to clear codes, reconnect and drive until light comes on (or doesn't). If light comes back, put old sensor back and replace other. Easy to do, 5 minutes if you soaked rust with oil! Be careful not to damage new sensor when swapping.

rm2001wj · 02-05-2009, 06:58 AM

Quote:

Originally Posted by mgrean

Hello-
.......
I picked up a new sensor today and when I got under the jeep I had no idea which sensor was bad. There is a dual exhaust so both sensors are right after mini catalytic converters, then the pipes join into the exhaust tube and head toward the rear. Is there anyway to figure out which is which or am I going have to trial and error?

Thanks, Mark

Sensor 2 is a sensor after a minicats. (Sensor 1 is in front of a minicat, so you have two Sensor 1s along with the two Sensor 2s.) For your I6, Bank 1 is the first (at the front, closest to the radiator) three cylinders while Bank
2 is the last three cylinders. Bank 1 Sensor 2 is the sensor after the minicat closest to the front of the engine.

The CA emissions diagram at this URL will make this clear. http://www.wjjeeps.com/oxygen_40.jpg

irishmarco · 02-05-2009, 07:23 PM

Figured the "dual exhaust" was each manifold on the V8, oh well....never studied the exhaust on my XJ (4.0).

wonderbrd937 · 02-05-2009, 08:29 PM

i have the same code p0138 and i had picked up the bosch oxy sensor, hopefully the light goes off

**the88thpianoman** · 02-05-2009, 08:35 PM

Quote:

Originally Posted by wonderbrd937

i have the same code p0138 and i had picked up the bosch oxy sensor, hopefully the light goes off

Return it and get a mopar.

wonderbrd937 · 02-05-2009, 08:36 PM

ill have to pass on that, my pockets aren't filled with money, and i have to see if i need it first, im going to take it out and clean it.

**the88thpianoman** · 02-05-2009, 08:38 PM

Quote:

Originally Posted by wonderbrd937

ill have to pass on that, my pockets aren't filled with money, and i have to see if i need it first, im going to take it out and clean it.

Getting the mopar sensor from kolak will cost maybe ten bucks more. Don't install the bosch, then you might not be able to return it and you'll be out that much more money once you've bought both. Trust me on this... others on here will tell you the same: Jeeps do not like bosch O2 sensors. Return it.

mgrean · 02-05-2009, 10:15 PM

from the general consensus here I will say I regretfully already bought and installed the bosch sensor. I have not disconnected the battery/reset the computer, but the problem has not gone away. tomorrow I will reset and then try swapping the sensors if they still read the same.
also, as the jeep is struggling to stay alive the lights dim and brighten with the rpms. I would guess this to be an alternator problem but the new battery checks out and I had the alternator tested a few days ago and it's apparently fine. thoughts?

thanks, mark

kentman · 02-06-2009, 05:57 AM

CA emissions suck. It is just a bunch more crap to go bad and cause pain and suffering down the road. Who ever heard of four O2 sensors on an I6? That is crazy. Why not just have twelve O2 sensors, two for each cylinder. That could make our air quality better.

When I bought a Bosch for the WJ (Bank 1 / Sensor 2 on the 4.7L HO), it was completely the wrong size. I returned it and bought a Mopar one. That one fit perfectly.

Regarding power, you could check the belt and the ground connections. You could even have water or PS pump problems slowing the belt down or making the belt slip. Check the tension, too.

mgrean · 02-06-2009, 09:18 AM

after searching through the forums a bit, the following seem like likely culprits...
1. throttle position sensor
2. idle air control
3. vent control\vacuum leak
4. egr valve vacuum line.

one of the codes read before said I had a vacuum leak, and one of the other threads stated the exact same problem I have was fixed by fixing the egr valve. however, after looking in my Haynes manual, my model does not have an egr valve. so, back to the drawing board.

mgrean · 02-06-2009, 09:21 AM

forgot to mention, regardless of the setting, air only blows out of the defrost vent.

QuadraTokn · 02-06-2009, 09:25 AM

Quote:

Originally Posted by wonderbrd937

ill have to pass on that, my pockets aren't filled with money, and i have to see if i need it first, im going to take it out and clean it.

Ronnie, Listen to the other guy. I had a Bosch sensor once and - no joke - It ran as good as a bad OEM sensor.

And dont even try cleaning it, it wont work.