Contour Enthusiasts Group Archives Forums General Troubleshooting O2 sensor CEL

I've had the Check Engine Light on on my 99 SE for about a week. I had it checked at Auto Zone and they gave me the codes P1131 and P0133. He said it is the O2 sensor in bank 1. Where is bank 1 and is it easy to replace?

Thanks

Your Duratec has two O2 sensors on each bank. The first set is on the exhaust manifolds before the converters, the second is downstream in the exhaust. Bank 1 is against the firewall. It's not an easy job. Some people can replace from top after components are removed, others get it from below or I think, through the wheel well. A special socket is required. You may want to have an experienced mechanic do it.

Al

For the 2.5L V6: the rear upper sensor is not THAT hard to replace. Bank 1 is the rear bank, and P1131 means the upper sensor, before the cat. The rear upper 02 sensor is definitely the hardest of all 4 sensors to replace but it is doable. Having wrists that aren't fat helps .

I worked from above and below to get access to that little bugger. There is no need to get in through the wheel well. As a matter of fact, going in through the wheel well will never get you near the sensor.

Anyway, when I did mine, I used the following tools:

misc sockets to remove coil packs
7/8" combo wrench (box end + open end)
Liquid wrench to loosen old sensor

There is a special 02 sensor socket out there but I did not use it.

That's all that comes to mind right now, but there may have been other standard tools used along the way.

For detailed instructions, do a search on '02 sensor replacement'. Someone out there wrote a detailed guide....

Yup, the sensor is hard to get at, but not impossible. I found it easiest to lay a flattend out box on the UIM so I had a place to neel down on top of the engine. A flashlight, a 3/8" breaker bar, and an O2 socket did the trick. IIRC there is a fuse/link or big wire down in that area that likes to get in the way.

My experience with this , for what it's worth.