When the check engine light appears on your dashboard, it can elicit anything from mild annoyance to immediate panic. The function of the indicator is to alert the vehicle owner of an issue that the electronic-control system cannot correct itself.

Part of the nuisance with the check engine light is how vague it is. There are many reasons why it might be activated in your Mercedes-Benz, and some are much more serious than others. To help put your mind at ease and allow you to know when to call Tanner Motors, we have put together the top 5 most common reasons your check engine light is illuminated, and how to properly address them.

Types of Check Engine Light Illuminations

There are more than one ways the check engine light can activate. The first step is identifying if the light is coming on intermittently, flashing, or is constantly on. This will help point you in the right direction when troubleshooting.

If the light is coming on inconsistently, or only under certain circumstances, pay attention to your vehicle’s performance to see if it differs while the light is on versus off. This could indicate something on the cusp of failing, and should be addressed right away.

If the light is blinking rapidly, it is indicating to the driver that it may no longer be safe to be operating the vehicle. In this instance, it is crucial that you pull over and have your car towed.

If the light is constantly on, the diagnostic system has detected something, even if you may not notice any performance issues. It is not necessary to stop driving when this happens, but still recommended to get your vehicle serviced at your earliest convenience. If the light is on and you notice a sharp decline in your vehicle’s performance, your vehicle is intentionally reducing its functions in order to avoid further damage. In this case, you should stop operating your vehicle and have it towed.

Top 5 Common Causes

There are a myriad of reasons as to why your check engine line is illuminated in your Mercedes-Benz. Ultimately, an experienced team of mechanics specializing in Mercedes-Benz will be the ones to properly diagnose and resolve the issue, but here are the 5 most common explanations:

• Loose, Broken, or Missing Gas Cap: The gas cap acts as a seal, maintaining your engine’s pressure and preventing fumes from escaping. If the cap is not properly sealed, or is broken or missing, your vehicle’s fuel efficiency could drop, and you may even notice some jerkiness while driving. Once you’ve ensured that the gas cap is in good condition and properly installed, the check engine light may need about a day before it turns off again. If it does not turn off by itself, the computer system can be reset by Tanner Motors.
• Damaged Catalytic Converter: Possibly the worst-case scenario, a failure in the catalytic converter can indicate something else in the engine is faulty, and should be addressed immediately. The catalytic converter functions to filter toxins out of the carbon monoxide. If it becomes clogged or broken, you risk not only your vehicle’s performance, but also dumping toxic emissions into the environment unnecessarily.
• Malfunctioning Spark Plugs and Wires: Replacing spark plugs should be part of your regular vehicle maintenance schedule. The spark plug is responsible for creating the initial spark that ignites the engine’s combustion. Without this spark, your vehicle’s engine may misfire, and eventually cease to start. This is a preventable problem if you follow your manual’s recommended service routine.
• Faulty Oxygen Sensor: The oxygen sensor’s role is to monitor how much unburned oxygen is in the exhaust of your Mercedes-Benz. The air-fuel ratio in your engine is one that relies on a very specific balance for your car to operate properly, so this measuring system needs to be functioning at its best. If the oxygen sensor gets dirty or damaged, too little or too much fuel may be sent to the engine. Ultimately, this can be one of the causes of a damaged catalytic converter. It’s important to have this serviced right away to avoid costly damage to multiple parts of your engine.
• Faulty Mass Air Flow Sensor: Similar to the oxygen sensor, the mass air flow sensor measures how much air is coming into the engine, and your vehicle’s computer then uses that data to measure how much fuel is needed. This imbalance in the air-fuel ratio can cause your car to stall, as well as release unnecessarily harmful emissions while driving.

Other less common reasons for the check engine light to come on are an aftermarket alarm (indicating a flaw in the vehicle’s installation), a vacuum leak, an exhaust valve failure, or a dead battery. Our experts at Tanner Motors will be able to diagnose which of these is the issue and address it with care and precision.

Quality and Reliability in Phoenix, Arizona at Tanner Motors

For drivers in the Phoenix area, the team at Tanner Motors helps you get back on the road quickly. For years we’ve been the area’s number 1 dealership alternative for Mercedes-Benz services and repairs. Call us today at 602-241-9888 to schedule the appointment your car deserves.