where is the oxygen sensor located on a chevolet colorado truck?

Answer 1

all O2 sensors are located in the exhaust pipe just after the exhaust manifold. (usually putting them very close to the firewall and hard to get at).
there are sometimes aux sensors located near the converter.

specifically, for your vehicle i can't say.

Answer 2

start at the exhaust manifold and follow it down until you hit the o2 sensor

Answer 3

Should be a couple before and after the catalytic converter.