Where is the o2 sensor located? The pervious owner of my 94 pickup put a flow master on it and messed around with everything. where is the o2 sensor usually go and how would you test it to see if its dead? Thanks.

 

It's right before the Catalytic converter (and if you're in CA, also right after the Cat).

The easiest way is jumper TE1 to E1, read the voltage (to E1) on Vf1. That's the amplified O2 sensor, and it should swing back and forth from about 0.5 volts to 5 volts 8 times in 10 seconds.

If you're not getting anything at Vf1, try Ox1. Thats the raw O2 sensor voltage, about 0.2 to 0.9 volts. Last but not least, if you're not getting anything there you might try checking the wiring before laying under the truck with a voltmeter on the hot O2 Sensor.

 

Ok ill test that, i was also wondering the location of the cat? whoever owned this truck before me cut it off so im not sure if he messed around with the location of the o2 sensor also. Thank you.

 

CA emission has 2, one before & one after the CAT>

If you don't see something similar to a spark plug about 2 feet after the downpipe connection to the manifold, it's gone.