Originally posted by BIGS:
Originally posted by Tony2005:
What is the exact CEL code? Bank 2 Sensor 1 is radiator side Upper (before precat).

This thread has a picture.
http://www.contour.org/ubbthreads/showflat.php?Cat=&Board=trouble&Number=1269675&Forum=trouble&Words=bank%202%20Upper&Match=Entire%20Phrase&Searchpage=0&Limit=25&Old=6months&Main=1267959&Search=true#Post1269675




Its funny how you would expect someone at a parts store to know which bank and sensor go where on a engine, but i have every guy at the parts store tell me a different answer, none that were what you said. One guy said that the bank 2 sensor one, was after the cat, the other said it was before, which is right, and the manager said it was the one facing the firewall, but none said it was the one by the radiator. heres my only question, i replaced the 02 sensor by the firewall within the last 1 1/2 years, and cant remember if the 02 sensor i replced(stock ford) had a white cable or not. see the pre cat sensor i replaced by the firewall has a red cable(bosch), while the one by the radiator has a white cable(im assuming its still stock). I know the harness is the same on the fronts, and the backs(after cat), but the color of the 02 sensor i got know is also red. SO, do the manufacturers make the same color wire for each sensor, or do i ignore all the bull#### and just replace the white 02 sensor i have up by the radiator? because that indeed is the bank 2 sensor 1. right?
too much confusionover a simple task, but i wanna be sure because the sensor by the firewall is a pain to change. thanks



Tony gave you the correct answer. Bank 2 is the front bank. it is bank 2 becvause of the cylinder numbering protocol.

The cylinders are numbered as if the engine were in a rear wheel drive car. Ford has always called the front right cylinder number 1 on a rear wheel drive car. Twist the engine sideways for front wheel drive and the numbering stays the same. That makes bank 1 the rear bank with cylinders 1, 2, & 3 on a V6 Contour. Bank 2 is is the front bank with cylinders 4, 5, & 6.

The oxygen sensor that functions to aid in fuel mixture is always upstream of any cat. The oxygen sensors that are downstream of any cat are used as cat effeciency monitors.

So the oxygen sensor for bank 2 that helps control fuel mixture would be the one in the FRONT exhaust manifold and it would be UPSTREAM of the pre-cat which is also located in the exhaust manifold. Of the two on the front bank, it would be the TOP on.

Tony even gave you a picture. He's trustworthy. I think the parts guys are just ignorant (they just don't really know).


Jim Johnson 98 SVT 03 Escape Limited