How do you replace the coolant sensor on a 2004 Saturn Ion?

To replace the coolant sensor on a 2004 Saturn Ion, first, ensure the engine is cool and disconnect the negative battery terminal to avoid electrical issues. Locate the coolant temperature sensor, which is typically found near the thermostat housing on the engine. Remove the electrical connector and unscrew the old sensor using a socket wrench. Install the new sensor, reconnect the electrical connector, and reattach the battery terminal, ensuring to refill any lost coolant if necessary.