Coolant fan temp sensor location on a 2003 chevy venture

Bad coolant temp sensor is my main opinion

there is a very common problem with all GM cars and trucks ,and that is the intake manifold gasket leaks. have the motor pressure tested. here is a picture of a bad intakr gasket I did last week

There are two one for coolant fan and one for engine temp . engine temp is usally located in the side of the head on driver side by exhaust manifold .
coolant fan temp sensor is located on the intake near the thermostat housing .

code p 0481 refers to coolant temp fans --circuit malfunction===causes-- wiring--- , fan--ECM
fix the fan not working --fuses wiring fan motor
codes p 0132 and 137 and p 0141 refer to the heated oxygen sensors in the exhaust manifolds , both banks before the cat converters
replace those sensors and it will fix those codes

the sensor located at thermostat housing is for the temp gauge..i am still looking for this myself

This may bye an issue with the coolant temp sensor.Try unplugging the sensor and the fans should come.The sensor is located towards the front of the engine on the drivers side by the upper radiator hose.

its at the end of upper radiater hose at housing for thermostat.

either the temp sensor is bad but, it sounds like the fan relay is stuck.
replace the relay its in the fuse box.

The PCM may be defective.

the computer turns the cooling fan , using the ECT sensior in on the manifold