2018 Mercedes-Benz AMG GT Has A Check Engine Light

Common Causes for the Check Engine Light in Your 2018 Mercedes-Benz AMG GT and How to Resolve Them

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Reviewed by
Aisha
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 2018 Mercedes-Benz AMG GT 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 2018 Mercedes-Benz AMG GT 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.

What are the initial diagnostic steps to take for a check engine light on a 2018 Mercedes-Benz AMG GT?

When faced with a check engine light on your 2018 Mercedes-Benz AMG GT, it's essential to approach the diagnosis methodically. Start by checking the gas cap; a loose or damaged cap is a common culprit that can easily trigger the light. Next, examine your dashboard for any additional warning indicators or messages that might provide further insight into the problem. Utilizing an OBD-II scanner is a crucial step, as it allows you to retrieve error codes from the vehicle's computer, which can direct you to the specific issue at hand. Additionally, inspect the engine bay for any visible signs of damage, such as frayed wires or loose hoses, which could indicate a more serious problem. Finally, pay attention to how your vehicle is performing; symptoms like rough idling or stalling can be significant clues. By following these steps, you can effectively narrow down the cause of the check engine light and determine whether it's a simple fix or if further investigation is needed.

What are the common problems that could cause the check engine light to illuminate in a 2018 Mercedes-Benz AMG GT?

When the check engine light illuminates in a 2018 Mercedes-Benz AMG GT, it signals that something may be amiss under the hood, prompting DIY enthusiasts to investigate. One of the most straightforward issues to check is a loose gas cap, which can easily be tightened to prevent fuel vapors from escaping. If the light persists, consider examining the oxygen sensor, as a malfunction here can significantly impact both fuel efficiency and emissions. Additionally, the catalytic converter is crucial for reducing harmful emissions, and any issues with it can trigger the warning light. Another component to inspect is the mass airflow sensor, which regulates the air entering the engine; a malfunction can lead to performance problems. Lastly, don’t overlook the spark plugs and ignition coils, as faults in these areas can cause engine misfires, further illuminating the check engine light. By understanding these common problems, you can effectively troubleshoot and maintain your AMG GT, ensuring it operates at peak performance.

How urgent is it to address the check engine light in a 2018 Mercedes-Benz AMG GT?

When the check engine light illuminates in your 2018 Mercedes-Benz AMG GT, it signals an urgent need for attention. Ignoring this warning can lead to a cascade of problems, including diminished fuel efficiency and compromised engine performance, which may escalate into more severe mechanical failures. The sophisticated onboard diagnostics in modern vehicles can help identify the specific issue, but delaying a professional diagnosis could result in costly repairs and safety risks. Therefore, it is crucial to prioritize this warning and seek a qualified mechanic's expertise to ensure your vehicle remains in optimal condition and to prevent any potential damage that could arise from continued operation with an unresolved check engine light.

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