I am looking to replace my O2 sensors on my 2003 F250 5.4. I went under the truck to see how long the wires are on them to get the right length since there are different sizes. I can only find two sensors on the truck. One on each side of the exhaust manifold. I keep finding stuff(part stores, manuals) that says there is a down stream sensor--which is found after the cat--Right? but I can not find any other sensors. Is there not really any other sensor or am I just having a bad day. I looked and felt all down the pipes and could not find it. Please can someone clear this up for me.
Thanks, Michael

 

You may not have them on a F250. Some early ones didn't have the rear sensors.

 

If your truck was manufactured and rated for > 8500 GVW, it doesn't have downstream O2 sensors.

Check the 4th digit of your VIN. If it is N, S, W, X, A, H, J, K, L, or M, it is in this class and thus exempt from the full OBD-II requirement.

Steve

 

If it has the downs, I think it does since the LD's are 7700GVW, they are in the exhaust under the cab after the cats.

 

Thanks for the responce and after looking at the vin it is expempt. So I will only purchase the front two. Thanks for the info, Michael