Hello folks, new to the forums here. My old man posts here and told me you dudes were great for advice.

I just purchased a manual '96 F150, 4.9 with 127k on it. No engine light on when I bought it.

Today, it threw a code for "Lack of heated oxygen sensor bank 1 sensor 1", and indicated it was running lean.

I located three o2 sensors on the vehicle - 2 before the cat up top on the passenger side of the vehicle, and one post-cat.

Anyone have any idea which of these would be bank 1 sensor 1? The Haynes manual is zero help with anything o2 sensor. Any help would be greatly appreciated!

 

For the old SD EFI system the I6 was broken into two banks with cyls 1,3,5 on bank 1 and cyls 2,4,6 in bank 2, if your truck has a sort of double tri-Y setup on the exhaust this cylinder association will still apply for O2 sensor purposes.

 

Welcome, post up some pictures young man!