Case Studies

5 Reasons Your Check Engine Light May Be On (And How To Prevent It)

Understandably, most car owners dread the moment when the check engine light pops up on the dashboard. This is even scarier when they are on the highway or driving over long distances.

Simple fact is, the light can be attributed to a number of issues.

Most often it’s typically not an emergency or big repair. At Atlantic Motorcar Center or other qualified specialists,  can be able to diagnose the problem rather easily.

Since the mid 1990s, most modern day vehicles, Audi, BMW, Lexus, Mercedes-Benz, Mini Cooper, PorscheVolvo and VW, along with others, have on-board diagnostic systems that aid in identifying the particular issue that caused the light to pop up. Let’s take a look at the most common problems. We use the factory diagnostic commuter, in this case, the XNTRY Mercedes diagnostic computer, that connects to your car’s network to quickly and accurately identify faults. We then provide you with a full report, and estimate.

I. Replace Oxygen Sensor. This is the part that monitors the unburden oxygen from the exhaust and controls how much fuel is burned. A faulty sensor can’t provide the right data therefore causing a decrease in gas mileage.

Most cars have between 2-4 oxygen sensors and the code will tell you which one needs replacing. A sensor becomes faulty when it’s covered with too much oil ash and loses its ability to change oxygen and fuel mixture. A failed up oxygen sensor can lead to a damaged catalytic converter which costs in excess of $2000.

II. Loose or Faulty Gas Cap. The gas cap is the most common cause of check engine light popping up. When it’s seal is loose or cracked up, it then it allows fuel vapour to escape and can crate a fault in the fuel system.

This failure increases emissions and reduces gas mileage. When it indicates that the gas cap is faulty, pull over and retighten it. Examine the cap for any cracks or worn out edges. Continue driving for about 20 minutes and monitor if the engine light goes off. A typical gas cap costs about $20-25, at at any sign of cracking of the seal, the cap should be replaced, but be sure to use a factory part. A loose gas cap may not be risky but it leads to higher emissions, and can present a safety problem.

III. Malfunctioned Catalytic Convertor. The job of a catalytic convertor is to reduce exhaust gases. It converts carbon monoxide and other toxic substances in fuel into harmless compounds. If it’s faulty or failing, the gas mileage reduces significantly. Most catalytic convertors stay in top shape through regular maintenance, which is why a Check Engine light should never be ignored, but diagnosed promptly.

However, they can become damaged because of rusty spark plugs, or broken oxygen sensors etc. When it stops functioning the harmful gases will pass out through the exhaust into the environment. When a catalytic convertor fully deteriorates then it’s time to replace it.

IV. Faulty Mass Airflow Sensor. This device tells the car computer to add the needed amount of fuel based on the air coming through to the car engine. That’s why when it’s faulty the emissions will increase, the gas mileage will decrease, and the car may stall.

This is one of the reasons the engine light pops up on the dashboard. The mass airflow sensor usually fails when the air filter is not replaced, damaged through improper service, or when it wears out.

V. Faulty Spark Coils and Wires. Another reason the engine light might pop up is because of spark plugs and ignition coils. The spark plug seals the combustion chamber and provides the spark for initiating combustion in your engine. When they are worn and failing, often around 60,000 miles, they begin to misfire.

This problem is often marked by a little jolt when you start accelerating. Older spark plugs can be replaced after 60k miles while the newer ones can go a little longer. Still, plugs fail over time and there is little you can do about it.

Questions, or if we can be of help in any way with service on your Audi, BMW, Mercedes, Mini Cooper, Porsche, Volvo, VW or other European (and now Japanese) import, please contact us.
Our team of Service Specialists are here to help, for even the newest autos! (207) 882-9969.

Knowing, not just “doing”, that’s the Atlantic Motorcar Center way of life.

The Atlantic Motorcar Center Service Team

Accessibility Toolbar