All vehicles are incredibly complex machines, especially those which have been intelligently engineered and thoughtfully designed, such as BMW. Because of this, your car has a variety of systems in place to protect you and your car from the effects of severe part failure. One such system is the check engine warning light. Below, you can find out how the light works as well as the types of part failure which can cause it to illuminate.
What is the check engine light?
The Engine Management Light (EML) or check engine light is a warning indicator which is found on your BMW’s dashboard. It will illuminate when more severe issues are detected in your vehicle’s systems or parts which work with the engine and the connecting exhaust systems.
The engine management light connects directly to your BMW’s main computer, which is known as the ECU or Engine Control Unit. If the ECU detects an issue in one of the aforementioned systems, it will trigger the check engine light and send out an error code. This can be used to correctly diagnose and repair the problem.
How a driver should immediately respond to the EML depends on the severity of the issue. If the car still feels like its running fine, then lower your speed and drive it directly to a professional repair shop. However, if the EML lights up red or your car no longer feels safe, then pull over and call for a recovery vehicle to tow you to a repair shop.
Common Reasons Why the Check Engine Light may Illuminate
There are many reasons why this essential warning light may illuminate. Below, we have listed some of the most common reasons, how risky they are for your car, and how you should respond.
Vacuum Hose Leaks
Damage Level: Low
Response: Lower your speed and locate the nearest auto shop.
Vacuum hoses are needed to channel both fresh air as well as emissions around the engine to allow it to run correctly. They’re made of rubber and can be exposed to high temperatures inside the engine which can lead to them cracking or deteriorating over time. When this happens, the precise balance of gases can be thrown off-kilter, leading to the engine’s sensors reporting issues to the ECU.
Loose Filler Cap
Damage Level: Low
Response: Check the cap and replace as needed.
This issue is most commonly caused by drivers being distracted at the pumps and not correctly tightening their fuel cap. A loose cap allows extra air into the tank which distripts the pressure. This will cause one of the many sensors to detect an issue and inform the ECU. This is the most simple and most common cause for check engine light illumination and should always be ruled out first.
Fuel Pump Blockage
Damage Level: Medium
Response: Lower your speed and locate the nearest auto shop.
The fuel pump is what provides pressurized fuel to the fuel injectors. If the pump isn’t working correctly, then the fuel will not be able to be properly delivered to the engine, causing rough running. The engine light will be illuminated by the ECU and your BMW will likely be at an increased risk of misfires.
Soot on the Particulate Filter
Damage Level: High
What to do: Lower your speed and locate the nearest auto shop, or call for a tow.
The particulate filter is most commonly found in diesel models, but it is being introduced into gasoline cars too. The particulate filter is responsible for capturing the soot which is produced by the combustion process. If this filter becomes clogged, then this soot will settle inside the engine and start to contaminate the delicate parts inside. This issue needs to be resolved quickly as if the filter becomes damaged beyond repair, you are likely to be footing an expensive bill.
Turning Wrenches
Turning Wrenches of Louisville, KY are experts in 
repairing, servicing, and maintaining European vehicles. We are open Monday through Friday to serve you. Our dedicated team will be able to diagnose and respond to your BMW’s issue quickly, efficiently, and affordably. Our friendly team is dedicated to making sure you drive away happy and safely. We are so confident in what we do that we offer a 3-year/36,000 mile warranty as a guarantee on our work. Call us today or stop by to speak to our technicians.