Where is the thermostat located on a 2003 dodge neon?

The thermostat on a 2003 Dodge Neon is located on the engine, at the bottom of the engine, near the water pump. It's not easily accessible and requires removing some components to get to it. You'll likely need to consult a repair manual specific to your 2003 Dodge Neon for detailed instructions and diagrams to locate it precisely and for the proper replacement procedure.