Check Engine Light Evolution

History of Check Engine Lights

Have you ever wondered what it was like to drive a vehicle before all of today’s advanced technology? Cars come equipped with complex computer systems to make our lives easier. From parallel parking to maintaining lane control, today’s cars are closer than ever to driving themselves, but let’s not go down that rabbit hole. Drivers ought to appreciate their vehicle’s computer-assisted systems, such as the check engine light that monitors engine function. Without your vehicle’s electrical systems and early warnings, you’d probably end up stranded on the side of the road. But where did this technology come from?

Malfunction Indicator Lamps (MIL)

In the 1980s, new vehicles made use of the malfunction indicator lamp (more commonly known today as the check engine light). Early versions were frequently confused with existing “trouble” indicators, likened to an “idiot light” that only indicated serious engine trouble and imminent breakdown. Computerized engine controls had self-diagnosis functions for the first time, which meant they could warn drivers of engine problems in advance of breakdowns. The light on the dashboard told owners to seek professional attention soon. Code behind the alert could be read by a special device and technician to determine what repairs were needed. Today’s check engine lights work pretty much the same way, just with more accuracy!

The MIL illuminates prior to the engine starting, in the moments before drivers turn the key all the way in the ignition, to prove the light is not burnt out. When no fault is detected, dashboard warning lights turn off. Older vehicles that required multiple cranking attempts used MIL to indicate failed starts. If the light remained on, drivers needed to take another attempt to start the car.

Starting in the 1990s and 2000s, some vehicle manufacturers used MIL to remind drivers of maintenance intervals. For example, Mazda programmed the light to come on at 80,000 miles, regardless of engine health and function to encourage owners to visit for maintenance service. This kind of alert was known as an odometer trigger. Chrysler vehicles built in the early 1970’s used similar odometer-triggered reminders labeled, “Check EGR,” which were reset at a Chrysler dealership.