i have a 2006 XJ8 L and i have replaced the up stream #2 O2 sensor bank #1 twice, and the check engine light comes back on within a week with the same code. i have been using Bosch made sensors, and Jag uses Denso at the factory.. Could that be the reason? Does anyone have any other ideas as to what could be causing this to happen?? should i replace it again with a Denso?? could the computer be going bad?? the wiring has been checked and it is fine.. no exhaust leaks and the cat is NOT clogged. so i am out of ideas......................HELP!!! please..

 

So what's the code you get?

 

The code is P0137. bank 1 sensor #2 low voltage.. the car runs smooth and strong, no hesitation or smoke or rough idle etc.. there are no symptoms or any other apparent issues, just that darn light.

 

P0137 is a downstream sensor code

bank 1 sensor 2 = downstream

EDIT

I mean in your opening post you said you changed the upstream sensor.

 

PO131 is the front sensor i believe.. Bank 1 sensor 1

 

isn't the up stream the rear sensor???

 

now i am confused..

 

Upstream, Sensor 1, before the cat
Downstream, Sensor 2, after the cat

Before/after is in relation to the direction of the exhaust flow

Actually which code do you have? You first said P0137, but then you said P0131

P0137 = downstream sensor, after the cat
P0131 = upstream sensor, before the cat

Which sensor did you change?

 

I am getting the P0137 code. the sensor i put in has only holes around the front tip of the sensor, the one in front has them all over the tip.. i had some one put it in for me, i would think they would have told me if i had given them the wrong sensor.. or at least i hope they would.

 

okay i spoke with my mechanic and he said that i had given him Both sensors for bank 1 and he replaced them both, sensor 1 & 2 bank 1. so i should be fine, but i keep getting the ck engine light and the P0137 code he is at a loss to explain this problem as well. Thank you for being patient with me..

 

Possibly changed the wrong side sensors ? Bank 1 relates to which side of the car?

 

i spoke with the mechanic and he said he checked everything and he did not see anything wrong with the wire harness. so he changed the front sensor thinking that maybe one old and one new sensor was an issue.. but the light came back on with the same P0137 code again.. i don't think it is the sensor either, but some where in the harness, he just has to find it. i am broke and have to wait until i can afford to take it back to him and let him get into the harness again.. the light has stayed off much longer this time..

 

fwiw, back when I was wrenching...I did see different brands of sensors cause issues like this - they respond at different rates, perhaps different voltages.
I always use the same brand, certainly on the same side.

 

Just to answer the question about which is Bank 1 on the X350, here's the diagram from the Technical Introduction Dealer Training Manual:




Cheers,

Don

 

Following on from Dons info, has he changed the sensor on the correct bank of the engine, a simple visual check would suffice to eliminate the possibility, if he has get the mechanic to swap them over free as his error.

 

spoke to the mechanic and yes he did the corrct side, but he wants to take a coser look ant the connections to make sure none of the pins are bent. and he suggested to fli[p the sensors to see it the code changes with the sensor which would suggest a faulty sensor.. so we wait until i can afford to go back.. money is an issue, i also have a 740 BMW that i had a lot of work done to as well and i am broke!! so i have to wait.. i will keep you all informed to add insult to injury, the rear power sun shade died!!! Darn!!!
thank you to you all for your help.. don't know what i would do with out you,..