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What Is The Point Of My Check Engine Light?

The check engine light in most cars (lovingly referred to by auto enthusiasts as the idiot light) is a truly incredible little invention and a lifesaver for many modern vehicles. But, how did the check engine light come about; And what is the point of its existence?

In the good old days of motoring (and before computers ruled the world) cars were arguably very simple machines. Fuel and air went into the engine, things exploded, wheels went round and burnt gasses came back out the exhaust.

These cars relied heavily on mechanical feedback and general driver knowledge to operate properly and to prevent major failure. Mechanical gauges often cluttered up dashboards and being able to read the gauges was a genuine part of driving.

At one-point things like oil pressure, battery voltage, fuel pressure, timing, engine temperature and the choke were all directly monitored or controlled by the driver in some way.

As driving became more commonplace through the 1920’s-1940’s automotive manufacturers began to replace these gauges with analogue operated lights where possible. Instead of providing the driver with a gauge, a pressure switch would be inserted into the oiling system and switch a light on if the pressure was too low.

Time and further refinement of the automobile saw more and more of these gauges replaced with switches and lights, much to the demise of many drivers of the day who saw gauges as a way to detect and prevent issues with the car. Hence the rise of the term idiot light.

As cars began to get more and more advanced through the 70’s and 80’s and mechanical controls were switched out for computers (a common hitting point for our blogs), cars began to monitor the engines a lot more readily by themselves.

Whereas many older cars were only able to monitor things like oil pressure and engine temperature, modern computer-controlled cars began to recognise things like engine misfires, poor air flow or air leaks and even poorly burnt fuel through the exhaust.

Instead of making individual lights for all of these issues, auto-makers instead stored the faults on the memory of the computers and ended up with a catch-all light for each of the major systems such as engine, electrical, ABS and the airbags.

In modern cars, these lights can be caused by an absolute myriad (that's our 1 big word for the week) of things but, while they may seem annoying when they occur, it’s a great tool to help drivers know there’s a problem with their car before it becomes a major issue.


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