Exploding parts...

Electronic testing for a Check Engine Light reveals a mechanical failure... Disassembly and inspection found this Cooling System Thermostat broken up into several pieces causing the Engine to run too cold. The Electronic Temperature Sensor on this 2001 Plymouth Neon reported this lower than normal temperature to the vehicle's Computer which then alerted the driver of a potential problem by turning on the Check Engine Light. It's interesting how often high tech and low tech interplay with one another in the process of discovering and repairing problems with our modern cars and trucks.