2021 Mercedes-Benz C63 AMG S Smells Like Gas

Diagnosing Fuel Odor Issues in Your 2021 Mercedes-Benz C63 AMG S and Essential Safety Precautions

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Reviewed by
Bo Fader
Written by RepairPal Car Genius
Updated January 14, 2025
0%
15% chance it's the
Gas Cap
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40% chance it's the
Emissions Control System
0%
45% chance it's
Something else
The most common reasons a 2021 Mercedes-Benz C63 AMG S smells like gas are the gas cap, the fuel system, or the emissions control system.
  • Gas Cap: A loose or damaged gas cap can cause fuel vapors to escape, triggering the check engine light and potentially affecting fuel system pressure.
  • Emissions Control System: A faulty emissions control system can lead to increased hydrocarbon emissions and trigger the check engine light due to malfunctioning components like the EGR valve or O2 sensors.
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 2021 Mercedes-Benz C63 AMG S smells like gas?

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 failing catalytic converter can cause a vehicle to fail emissions tests and turn on the check engine light. The exhaust might have an unusual smell. A restricted catalytic converter can result in a loss of engine power.

» LEARN MORE: How to tell if your catalytic converter is failing

The check engine light will illuminate any time there is a failed EVAP system test. This will be indicated by the various on-board diagnostics trouble codes that are stored in the vehicle's memory. Also, in some models, there may be a popping sound accompanying the check engine light, as the leak detection pump continuously attempts to pressurize the fuel tank. The canister may also cause difficulty starting the engine, a rough idle, and poor fuel mileage.

The check engine light will illuminate any time there is a failed EVAP system test. This will be indicated by the various on-board diagnostics trouble codes that are stored in the vehicle's memory. Also, in some models, there may be a popping sound accompanying the check engine light, as the leak detection pump continuously attempts to pressurize the fuel tank. A fuel tank leak may also cause difficulty starting the engine, a rough idle, and poor fuel mileage. When a fuel tank is simply corroded to the point of failure, the exterior tank condition rarely shows damage. The inside of the fuel tank will be rusted or corroded, and rust flakes or other debris may be floating in the fuel.

For most vehicles, the only symptom will be a check engine light or fuel tank filler cap light illuminating on the driver instrument cluster. This is to signal that there is an evaporative emissions (EVAP) leak. In some situations, the vehicle may take longer than normal to start, or, more rarely, the engine may not start at all. on-board diagnostic (OBD) trouble codes will refer to EVAP system failures such as a small or massive EVAP system leak. Lastly, the powertrain control module may notice a lean running condition, which could even lead to random and infrequent misfires.

What could be causing a gas smell in a 2021 Mercedes-Benz C63 AMG S, and what diagnostic steps should be taken first?

When you detect a gas smell in your 2021 Mercedes-Benz C63 AMG S, it's crucial to approach the diagnosis methodically to ensure safety and effectiveness. Start with a thorough visual inspection of the vehicle, looking for any obvious signs of fuel leaks, particularly around the fuel lines, injectors, and under the car. If you notice any wet spots or strong odors, this could indicate a fuel leak that needs immediate attention. Next, focus on the fuel injectors; a faulty injector can lead to fuel seeping out, so check for any signs of leakage or damage. Additionally, consider the evaporative emissions system, which is designed to prevent fuel vapors from escaping into the atmosphere. Inspect its components for any cracks or disconnections that could be causing the gas smell. Lastly, don’t overlook the exhaust system; a leak here can sometimes mimic the smell of gasoline. By following these diagnostic steps, you can systematically identify the source of the gas odor and take the necessary actions to resolve the issue, ensuring your vehicle remains safe and reliable.

What could be causing a gas smell in my 2021 Mercedes-Benz C63 AMG S?

When you detect a gas smell in your 2021 Mercedes-Benz C63 AMG S, it’s crucial to consider several common problems that could be at play. One of the primary concerns is a fuel leak, which can stem from damaged fuel lines, faulty fuel injectors, or issues with the fuel tank itself. Addressing a fuel leak is vital not only for the safety of the vehicle but also to prevent further damage. Another potential culprit is a faulty or loose fuel cap, which can allow fuel vapors to escape, leading to noticeable odors inside the cabin. Additionally, problems within the exhaust system, such as leaks or a malfunctioning catalytic converter, can also contribute to a gas smell, as these components are responsible for directing harmful gases away from the vehicle. Furthermore, issues with the evaporative emissions system, including a defective charcoal canister or purge valve, may result in fuel vapors entering the cabin. Lastly, an engine misfire can cause unburned fuel to escape into the exhaust system, producing a gas smell, often accompanied by performance issues or warning lights. If you encounter this issue, it’s advisable to conduct a thorough inspection or consult a qualified mechanic to ensure the problem is accurately diagnosed and resolved.

How urgent is it to address the gas smell in my 2021 Mercedes-Benz C63 AMG S?

Addressing a gas smell in your 2021 Mercedes-Benz C63 AMG S is not just a matter of convenience; it is a critical safety issue that demands immediate attention. The presence of gasoline fumes can indicate a fuel system leak, which poses a significant fire hazard, especially in the confined space of your car. Ignoring this warning can lead to catastrophic consequences, including the risk of fire or explosion. Moreover, inhaling gasoline vapors can have serious health implications, leading to symptoms such as dizziness, headaches, and nausea, which can escalate with prolonged exposure. Beyond safety and health concerns, neglecting a gas smell can result in further damage to your vehicle's fuel system, potentially leading to costly repairs down the line. Therefore, it is essential to take any gas smell seriously and seek professional assistance promptly to ensure your safety, protect your health, and maintain the integrity of your vehicle.

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2021 Mercedes-Benz C63 AMG S Gas Smell Causes & Solutions