Mercedes-Benz S420 Service Light is on Inspection at your home or office.

The dashboard of every car produced after 1996 has the ability to communicate messages of various severity and importance to the driver through warning and indicator lights.

The Service (or Service Engine) light is a warning light that is connected to the engine control unit (ECU) of a vehicle. The ECU is the brain of the car and monitors a number of systems, including:

• Emissions: There are sensors throughout the engine management system on all cars manufactured since 1996 that alert the driver of any malfunction that will lead to unacceptable amounts of emissions entering the air.

• Engine temperature: Sensors in and around the engine can alert the driver to excessive operating temperatures, which may lead to engine damage. Typically, this warning will be accompanied by a Temperature, Engine Overheating, or Check Gauges light.

• Mileage: While vehicles have recorded mileage for many years, the ECU can also keep track of mileage between oil changes and other routine services.

There are many other components the ECU is capable of monitoring, and those also vary depending on the manufacturer and year of production.