How to diagnose Mercedes-Benz Check Engine Light (CEL) problems.
Is your check engine light on? Is it flashing? Did the check engine light come on while driving? Don’t panic.
Instructions on how to troubleshoot Check Engine Light / Check Engine light.
To complete this task, you will need a simple OBD II scanner. These diagnostic scanners are a must for all car owners. Within seconds you can find out why the check engine light is on. Here are some of the bestselling OBD II scanners on Amazon, several of them selling for under $15.
Locate OBD II port.
Look under the steering wheel, in the driver’s footwell. Underneath the dashboard is the port where you plug in your OBD II scanner. It is very obvious, and you can’t plug your scanner in the wrong port because it doesn’t fit elsewhere. Watch the following video if you need help locating the OBD II port.
- Turn the key to the second position. All the dash lights come on but do not start the car.
- Hit READ on the scanner. You will see codes such as P0300. Write all of them down if you have more than one. YOUCANIC full system scanner is shown in the picture below.
- If you are having trouble with a Mercedes-Benz, go to www.mercedesmedic.com/faultcodes/ to get an idea of your problem.
- If you want to do more research, use the Search function on Mercedes Medic or any other search engine to understand the problem better. On any search engine, enter the manufacturer and the code you got from the scanner. For example Mercedes-Benz P0300
What should I do if the Check Engine light comes on while driving?
- Make sure your engine temperature doesn’t go past the halfway mark. You don’t want your temperature gauge to be in the red, overheating zone.
- Monitor your dash to ensure the oil light doesn’t come on. Very unlikely, but if it does, you are in serious trouble. If your oil light comes on, STOP the car immediately. In this case, you would be better off towing the car home or to a mechanic.
- On the luxury cars such as Mercedes Benz, BMW, Lexus, and Audi, depending on the reason for the check engine light, the car may go into limp / emergency mode, and the transmission will no longer shift properly. Don’t panic. This is for safety reasons, and to avoid further damage to your car once you make it home, use the OBD II scanner to get the fault codes.
Top Reasons Why your Check Engine Light is On.
- Loose fuel cap or damaged cap. If the fuel cap is not tight or not sealing properly, the Check Engine light will come on. The car will test the fuel system to ensure it can hold pressure. If it fails this test, then you will get CEL. If you have an OBD II scanner like the one mentioned above, you can know if this is your problem.
- Oxygen Sensor O2 Your car has a few oxygen sensors, typically between 2 to 4. They measure the unburned oxygen. You may also get poor fuel economy if your Check Engine Light is on because of the O2 sensor. The input values from the O2 sensor are used to adjust the fuel delivered to the engine. You can get O2 sensors at a fraction of dealer prices on Amazon that will fit Mercedes Benz. Check this one here, for example.
- Bad Catalytic Converter If these go bad, they start to get clogged. If that is the case, you will lose much power, and the car will feel sluggish, especially going uphill. You are looking at $200 to $400 for a universal cat and $600 to $1200 for an exact fit.
- Mass Air Flow Sensor MAF The MAF measures the air going into the car and, in some cases, the temperature of the air to adjust the fuel mixture ratio properly. They get dirty and malfunction. You may get away with cleaning yours, but a new one may be worth it. You can get one for $50 or even less on Amazon.
- Bad Spark Plugs / Wires / Spark Plug Coils Newer cars don’t use spark plug wires. Instead, they use spark plug coils that sit right on top of the spark plug. Either way, if you have an older car with wires or a newer one, these components could cause the check engine light to come on. Your Check engine light will flash on the dash. If you scan the car, you will get a code such as P0300, P0301, or P030* Check these spark plugs on Amazon and read some reviews before you buy.
What is the best scanner to use to diagnose a Mercedes-Benz?
The YOUCANIC full system diagnostic scanner is essential for troubleshooting Mercedes-Benz problems. This powerful diagnostic tool can help identify and diagnose issues with your vehicle’s engine, transmission, brakes, and other critical systems by reading and interpreting fault codes stored in your car’s computer system. With detailed information about the problem, you can make more informed decisions about repairs and maintenance, potentially saving time and money on costly repairs.
In addition to its diagnostic capabilities, the YOUCANIC scanner can also perform diagnostic tests on various systems, including the ABS, airbag, and steering systems, to help pinpoint the root cause of any issues. Whether you’re a DIY mechanic or a professional technician, this tool can help you diagnose and solve even the most complex automotive problems quickly, making it an essential tool for anyone who wants to maintain their Mercedes-Benz and keep it running smoothly years to come. With the YOUCANIC scanner in your toolbox, you can confidently approach any Mercedes-Benz problem, knowing you have the tools and knowledge to tackle any issue.