The Difference Between Check Engine Light and Service Light

It could be frustrating, to say the least, when you look down at your dashboard and see a warning light. Modern cars are filled with electronics and packed with sensors to monitor both how your vehicle is behaving and to make our motoring life easier. These warning lights can mean a variety of auto repair problems and can be a difficult task trying to work out exactly what that warning light flashing away on your dashboard is trying to tell you. It’s important to know what the car dashboard warning lights mean. These warning lights can pre-empt a car breakdown or full-on failure, potentially saving you from an expensive auto repair bill. Here are a few lights that you should pay attention to that will help you save money in the long run.

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:


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.


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.

The “Check Engine” light is there to help warn drivers of a problem with their car’s engine and other related systems. A blinking or flashing dashboard check engine light usually indicates a more severe problem. When this occurs, it’s best to limit your driving, check your vehicle service manual and schedule an appointment to have the problem looked at by a professional technician as soon as possible. Here are a few common things that can cause your check engine light to come on including:

O2 Sensors

Your oxygen sensor measures the amount of unburned oxygen in your vehicle’s exhaust system.

Gas Cap

Your gas cap seals the fuel system and helps maintain pressure within the fuel tank. It also prevents gasoline fumes (hydrocarbons) from being released into the atmosphere while you aren’t driving your car.

Catalytic Converter

Your catalytic converter helps protect our environment by converting harmful carbon monoxide into carbon dioxide. Damage usually occurs due to neglected maintenance

For more information on check engine lights, we recommend reading more here. When looking for a place to have your lights checked be aware that a parts store is in the business to sell parts, they are not in the business to diagnosis your auto repair light problem. Therefore, we recommend going to an automotive specialist who can help find the exact problem to help you save hundreds even thousands of dollars depending on the make and model of your vehicle.

Written by LMC Complete Automotive

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