OK, I for the good ol' CEL a few weeks back and it gave me the 0409 can 0304 codes. I've since changed both the rear bank o2 sensor and the knock sensor. The 0304 (knock sensor) code hasn't come back, but the 0409 code would stop showing up. Any ideas why this may keep coming back??? Also, this seems to have started shortly after my alternator died. Coincidence or cause? HELP!!

 

Test the o2 sensors with a multimeter to verify that indeed the sensors are bad, if they arent that could be a good start right there.

 

0409 is the right bank (front of the car) upstream (before the cat) oxygen sensor.

Perhaps your looking at the wrong sensor.

 

The right bank is the the one on the back side of the engine bay, before the cat. I think I have the right one.

MDeezy...I have a volt/ohm meter. Just tell me how to test them.

 

njmaxseltd is right the right back is the front of the car the o2 sensor closest to the front of the car.

Right bank is cylinders 2,4,6 which is at the front
Left Bank is cylinders 1,3,5, closer to the firewall.

I looked up 0409 and its undefined. As for testing I'll have to post later the numbers you'll need to check for, dont have my haynes with me at work.

 

Cylinder numbering is correct, but the right bank is the one closest to the firewall.

 

SHiit, then I just ordered the wrong o2 sensor. . .

 

Just cut the harness off the old one and solder it to the new sensor.

 

I'll do that if he's shipped already, bought off an org member and are going to ship this afternoon, so hopefully he comes on before then.

 

Actually the 2 front sensors are identical, except for harness length. If you look at www.oxygensensors.com, they sell you the same sensor and harness (since the harness length difference is marginal) for both front spots.

So you should be fine using the one you bought for either the RH or LH bank.

 

Thanks for that info I was scratching my head yesterday wondering if the front two were really different or not.