I see it mentioned in my Toy Factory Manual (no clear location). I see part numbers on the Internet. But I do not see the oxygen sensor anywhere on the truck. Where should the O2 sensor be located? Did some models come w/o an O2 sensor in 1980 since mine is a Cali model? Any help is appreciated!!!

Not sure if they had them back that far. On the carbed trucks, all it affected was some rudimentary mixture control for the cat's benefit.

First place to look would be on the outside of the manifold itself, and if not there, then on the pipe ahead of the cat.

Wouldn't be surprised if you didn't have one at all, though.

More info on that sensor ... Not an O2 kind of sensor but an exhaust gas temperature sensor (EGT) that tells the computer when to shut down Air Injection so as not to burn up the Cat.


:Yeah I found it. It's on the back inside of the catalytic
:converter. The wire runs in the cab and the connector is
:under the driver seat. In the manual it's called the CCo
:sensor ... I guess they didn't call them Oxygen sensors
:yet. It sends signals to an "emissions computer" which
:basically tells vacuum valves when to open. Those valves
:let the Air Injection system recirculate to the exhaust
:manifold. Why is it important? The AI system controls CO
:levels in exhaust. The CO levels are why my truck failed
:emissions.

By the way always replace mushy vacuum lines. I learned this by trial and error. The mushy lines I finally tested leaked like a sieve though there was no visible tears or breaks.