Hi Folks
Have fault in bank2 sensor 1 (upstream?) Mechanic that inspected it said bank 2 is driver side and bank 1 is passenger side of vehicle. Parts store guy says it's the opposite. So who's right? Thanks for the help
kbgrn150

 

Unless I am badly mistaken, Bank 1 is the side with #1 cylinder.
In the case of the 4.2, #1 cylinder is the front cylinder on the passenger side.
To verify, you can always look at the coil pack, find the #1 wire (connections are numbered with small numbers molded into coil pack assembly) and follow the #1 wire to the #1 cylinder.

 

Bank 2 sensor 1 was easiest for me to reach through the drivers side (left) wheelwell by turning the wheel full lock left.

 

Replace both sides.

 

If money's tight, all you need to replace is the one throwing a code. I would bet that is why he wanted to know which side is which.

 

howdy ,did u find out which one it is ? my trucks outside now n i dont know which one . ! .ive got the sensor and the socket . im learning how to do this stuff myself id like to believe ur mechanic ! but its looks like 2 ,one on each side 2003 f150 xl 4.2 6cyl thx frnd .....mike

 

Always replace 02 sensors in pairs.(Unless your vehicle only has one)

 

bank 1 is no1 cylinder bank 2 is no2 cylinder on the 4.2 v6 no1 should be right side or passenger side

 

You are correct. Replaced this a month ago.

 

And? Did it fix the problem?

 

Yep. No more check engine light. Didn't replace in pairs though. Just replaced the one side.