Mercedes-Benz E350 Has A Check Engine Light

Common Causes of the Check Engine Light in Your Mercedes-Benz E350 and How to Resolve Them

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Reviewed by
Devin Cabugcal
Written by RepairPal Car Genius
Updated January 14, 2025
0%
40% chance it's the
Emissions System
0%
60% chance it's
Something else
The most common reasons a Mercedes-Benz E350 has a check engine light are an emissions system component, a sensor, or a catalytic converter.
  • Emissions System: A faulty emissions system component, such as an oxygen sensor or EGR valve, can lead to increased emissions and trigger the check engine light.
Proper diagnosis will determine the exact cause of your symptom, saving you money on unnecessary repairs. The diagnostic experts at RepairPal Certified shops have the right tools and experience to solve any symptom.

How much does it cost to fix a Mercedes-Benz E350 has a check engine light?

Common Repairs

The total repair cost will vary based on the condition of your vehicle and the number of repairs needed to fix your symptom. Proper diagnosis will save you money by finding the exact repairs needed to fix your car right the first time.

A faulty oxygen sensor is one of the most common causes of a check engine light. Symptoms may include a decrease in fuel mileage, hesitation or misfiring from the engine, rough idling or even stalling. A faulty sensor may cause the vehicle to fail an emissions test.

Any time there is an emissions fault the check engine light will be displayed. The purpose of the check engine light is to inform the driver that an emission related fault has been found, and that there are on-board diagnostic (OBD) trouble codes stored in the powertrain or engine control module. Additionally, since the emissions systems are so intertwined into engine control and transmission control systems, symptoms may include nearly any sort of drivability concerns. This may include harsh shifting, failure to shift, hesitation on acceleration, jerking, engine failure to start or run, loss of power, or any number of other drivability issues.

Due to the nature of electrical systems on modern vehicles, the range of problems these can cause are nearly limitless. However, there is a way to categorize them in two ways. Permanent and intermittent problems. Permanent problems appear and remain. This may be the vehicle will not start, the radio does not work, or the door chime will not turn off among many, many others. These problems are more straight-forward to diagnose since they present themselves at all time. This means there will always be a fault to find. Intermittent electrical problems, however, can be difficult or impossible to locate, since they appear then disappear without warning. The best case scenario for an intermittent issue is when replicating the problem is easily accomplished and understood. This allows a technician to make an issue semi-permanent, allowing them to find the fault. Other issues that come and go without warning and cannot be replicated on demand must occur when the technician is servicing the vehicle, otherwise there is no problem to correct. It is most important to understand that electrical system faults always require inspection, and can include the vehicle working in any manner, or not working at all.

Like we noted in the last section, general diagnosis symptoms are the most vague of the bunch. There are several diagnostic spectrums, electrical diagnosis, drivability diagnostics, engine diagnostics, transmission diagnostics, and the list could continue for about 5 or 10 more spectrums of diagnostics. The most important take-away here, is that general diagnostics are diagnostics that have no other spectrum in which they fit, or the problem is unknown. This means that any vehicle left outside of a repair facility with the keys and an authorization to perform diagnosis will be diagnosed under the general diagnosis spectrum.

When the Check Engine Light comes on, you may experience engine performance issues such as poor acceleration, rough idling, or an engine that won't start. In some cases, no abnormal symptoms will be experienced. Other systems like the transmission or ABS can cause the Check Engine Light to illuminate and lights for those systems can come on at the same time. Similar lights may say "Check Engine Soon", "Malfunction Indicator Light" or just "Check". In rare case the engine can overheat.

Troubleshooting Check Engine Light in a Mercedes-Benz E350

When faced with a check engine light in your Mercedes-Benz E350, the first step is to conduct a thorough diagnosis to pinpoint the issue. Start by using an OBD-II scanner to retrieve any trouble codes, which can provide valuable insights into what might be wrong. Common triggers for the check engine light include issues with the oxygen sensor, catalytic converter, or spark plugs. After identifying the specific code, research the potential causes and solutions, focusing on simpler fixes first, such as checking for loose gas caps or faulty spark plugs. If the problem persists, delve deeper into the vehicle’s systems, examining components like the fuel injectors or mass airflow sensor. Once you’ve addressed the underlying issue, you can reset the check engine light using the scanner or by disconnecting the battery. However, remember that resetting the light without fixing the problem will only lead to its return. If the light continues to illuminate or if it starts flashing, indicating a more severe issue, it’s crucial to seek professional assistance to avoid further damage to your vehicle. By following this structured diagnostic approach, you can effectively troubleshoot the check engine light and ensure your Mercedes-Benz E350 runs smoothly.

What Could Cause the Check Engine Light to Illuminate in a Mercedes-Benz E350?

When the check engine light comes on in your Mercedes-Benz E350, it can be a source of concern, but understanding the common problems can help you diagnose the issue effectively. One of the simplest causes could be an unsecured gas cap; if it’s loose or damaged, it can lead to fuel vapor leaks, triggering the light. Another frequent culprit is a faulty oxygen sensor, which plays a crucial role in monitoring the exhaust and ensuring optimal fuel efficiency. If this sensor fails, it can lead to poor engine performance and increased emissions. Additionally, spark plug issues can also cause the check engine light to illuminate; worn or damaged spark plugs can result in misfires and reduced engine power. Lastly, problems with the catalytic converter, which is essential for reducing harmful emissions, can also trigger the warning light. Addressing these issues promptly is vital to maintaining your vehicle's performance and preventing further damage, making it essential for DIY enthusiasts to be aware of these common problems.

Why is the Check Engine Light On in a Mercedes-Benz E350?

When the check engine light illuminates in your Mercedes-Benz E350, it serves as a critical warning that should not be ignored. The potential causes, such as a loose gas cap, faulty oxygen sensor, worn spark plugs, or catalytic converter issues, can lead to significant performance problems if left unaddressed. For instance, a simple loose gas cap might seem trivial, but it can affect fuel efficiency and emissions. On the other hand, a malfunctioning oxygen sensor or spark plugs can lead to poor engine performance and increased emissions, while issues with the catalytic converter can result in costly repairs and environmental concerns. Ignoring these warnings not only risks further damage to your vehicle but can also compromise your safety on the road. Therefore, it is crucial to diagnose and resolve the underlying issues as soon as the check engine light comes on, ensuring your vehicle operates efficiently and safely.

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