Here is a site to pull the trouble codes. Just need a paper clip and it will tell you if it is the sensor or not.
The sensor is easy to change...20 minute job. And it is cheap too! The sensor is near the thermostat. Just drain some coolant and take the old sensor out, put the new one in, refill the coolant and your done. When mine went I didn't even drain the coolant....If your fast enough you won't loose to much through the hole
Mike