Engine coolant temp sensor?

SOURCE: 2000 Saturn SL2 with DOHC

Did you check fuses?

SOURCE: cooling fan always runs with ignition on

try putting the electrical connector on the other way

SOURCE: My radiator cooling fan is not working. I have

If you have A/C, you can check the system from the PCM output through the relay and to the fan motor by turning on the A/C and blower (with the engine on, of course): the cooling fan motor should turn on and stay on for several minutes.

Also, as you may know, this vehicle has a one-wire temperature sender that controls the dashboard gauge, but nothing else. (This one connects to a dk.green/yellow banded wire -- or maybe green/white banded.)

The other, two-wire temperature sensor is the one that connects to the PCM. This one has one yellow and one black wire. I assume that this is the one that you replaced.

And, in principle, there's the PCM itself that could be giving an inaccurate temperature... but that's expensive, so let's not go there...

- Roy

SOURCE: I own a 1999 Saturn SL2 sedan. The car is losing

You have done everything right so far. Sometimes water leaks out when the engine is hot and evaporates almost instantaneously, a classic point is the seal on the water pump pulley shaft. To find such a leak you need to pressure test your coolant system. The normal operational pressure of a coolant system is 7lbs/sqinch at running temperature. The pressure test will put in 11lbs/sqinch and then monitor this over some time looking for a bleed down due to the leak. If a leak exists to the exterior of the engine you should be able to spot the seepage. The next test will be to run the engine up to normal temperatures and to monitor the pressure, if the pressure jumps to 15lbs/sqinch when still cold then this indicates an internal gasket leak as exhaust gases are pushing out of the cylinder in to the coolant. One check to make is to remove the plugs one at a time and inspect them. Sometimes if water leaks into cylinder it has the effect of 'washing' the specific spark plug clean.

SOURCE: check engine light is on and cooling fan runs

curious to know if you got this solved. Guessing downstream o2 sensor. did your vue idle high? act like it was getting too much gas? Let me know please.