What does it mean when my Check Engine light is on is a question many of our users have raised to us through our toll-free no and other means. The Check Engine light being on is quite common in older cars and it is something you need to attend in priority.

Why Is My Check Engine Light On?

To put it in simple words, it is the situation when your Engine Control Unit is confused. This happens when one or more of the sensors wired to your ECU (Computer that controls the engine) starts giving data that does not make sense or are outside the normally expected range.

Your car (unless you’re driving a classic or antique) uses a very sophisticated control system to manage the engine. It uses dozens of sensors around the engine compartment to feed vital data to keep your engine running at optimum level.

All parameters like temperatures, the amount of air flowing into the engine, the position of the crankshaft and pistons, etc to name a few. Based on precise analysis of this data, your Engine decides the amount of fuel injected into the cylinders, the timing of when the spark plugs ignite it, and even when the camshaft opens the valves.

When the data from one of these sensors gets outside a narrowly-defined range of acceptable values, several things happen inside the computer’s software. In order to let you continue driving the vehicle, the computer will substitute a default value, one that’s close enough to get you home. When this happens, the ECU will generate an error code and your Check Engine light will start glowing. Remember, it is not advisable to continue driving without diagnosing the error code and fixing it ASAP. Remember your engine is now assuming the sensor data and is not capable of delivering optimum performance based on real data from the malfunctioning sensor.

How is a Check Engine Light Diagnosed?

The car repair shop can then plug a scan tool into the diagnostic port (OBD Port) under the dash and download the trouble codes, giving the technician a starting point for his diagnosis. He can then use the scan tool to erase the codes and turn off the light after fixing the root cause of the error.

If My Car is Running OK With the Light On, Can I Ignore It?


Even though you might not find any noticeable change while driving, understand that your engine will no longer be able to self-tune its operation to adjust to varying driving and environment conditions. Neglecting this error is detrimental to your engine life.

Do not worry! Book your service at www.vehpal.com for servicing your car. We understand how valuable your wheeled companion is for you.

Happy Motoring!

Understanding Your Car – Check Engine Light

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