Hi,
My truck is a 2003, 4.7, Auto Quad Cab. It is throwing me a code P0420. There are no Cats on my truck, never has been since my 9 years of ownership.
Had a look last night, and there are two sensors in the exhaust. Both seem identical, as in three wires, coloured, Black, White and Blue. One sensor is a little further back along the pipe than the other. Question is..... Are both sensors the same ?? Upstream/Downstream ? Going too replace them both while I am there, and just want to check with more knowledgeable people than myself !! Many thanks in advance, Alan...........

 

Its the rear sensor throwing the code since there are no cats.

 

Thanks mate. So are the two sensors the same ? I could order a pair and just change them both as am underneath anyways ! Didn't know if the Upstream and Downstream were different ?

Alan..............

 

I think the only difference is the length of the wiring harness....

 

Thank you. As I am in Scotland, UK, it makes sense to order the correct parts to avoid return shipping if its the wrong part !!

Thanks,

Alan........

 

Replacing the downstream sensor won’t help. That one monitors cat efficiency. No cat, it will throw a code. There are cheaters out there though. Moves the sensor out of the exhaust flow. .

 

Yup. Got a pair of them ordered up as well ! Thanks again for your help. Its much appreciated !!

Alan..........