Hello all, would like to learn what the OEM part number is for the upstream O2 sensor on the driver's side bank for a 1999 F-150 4.6 XLT 4x4. It appears to have 3 wires connecting to it were as the down stream has 4 wires.
Thank you in advance

 

I recommend calling your local Ford Parts dept or Tasca Parts directly. Give them your VIN so they can match it up exactly.

 

All four O2 sensors should have four wires. Ford didn't use three-wire sensors any longer when that truck was designed and built. If your sensor only has three wires, that would mean it's either the wrong part or has been damaged.

The sensors on the left and right are interchangeable with the possible exception of wire harness length.

 

Thank you for your replies!