'94 GMC Yukon O2 Sensor question

[dodgedude99]

how many and what type of O2 sensors should this truck have?
i thought the TBI motors only had the the sensor in the drivers manifold, but this one doesnt have the bung drilled and tapped but it has the purple wire like all the trucks i see at the 'yard that have the sensor in the manifold.
its my step sons truck, when he was under it he found a sensor in the crossover pipe that had a 3 wire O2 sensor.

i was under the impression that all the TBI trucks were a single wire O2 sensor.

 

[Russell]

Sounds like someone did some modifications... A heated sensor down in the Y pipe should work just fine though

 

[AJMBLAZER]

They went to a 3 wire for better cold weather performance around '93ish. My '92 had one 1 wire in the d-side manifold but not long after they changed to the 3 wire in he pipe setup.

 

[63chevyll]

I thought the change was 94, but 93 it is.

93-95 would have one sensor and 3 wires, as the 96 and newer would have the 4 wires. And four sensors

 

[AJMBLAZER]

I know for sure some trucks in '93 had the 3 wire sensor in the pipe. I did mine on my '92 and the sensor was like $30 a good decade or so ago. Then my friend needed to do hers so I sent her to the store and it cost her like two to three times what mine did and when I actually laid hands on it the thing had three wires and wasn't under the hood where mine was! Figured it out after laying underneath it and seeing the stock one was a 3 wire as well.