2012 Mercedes-Benz S350 Smells Like Gas

Diagnosing Fuel Odor Issues in Your 2012 Mercedes-Benz S350 and Essential Safety Measures

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Reviewed by
Devin Cabugcal
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
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45% chance it's
Something else
The most common reasons a 2012 Mercedes-Benz S350 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 2012 Mercedes-Benz S350 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

When the fuel filter begins to clog, the engine suffers from fuel starvation. This will cause a significant reduction in power and may also cause a misfire. These conditions may be intermittent, or constant and worsen over time. As the issue progresses, the engine may being to stall immediately after starting, fail to start, hesitate under throttle, or stall at particular angles on hills.

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 are the potential causes and diagnostic steps for a gas smell in a 2012 Mercedes-Benz S350?

When you detect a gas smell in your 2012 Mercedes-Benz S350, it's crucial to approach the situation methodically to identify the root cause. Begin with a visual inspection of the vehicle, looking for any obvious signs of fuel leaks around the fuel tank, fuel lines, and engine compartment. Next, check the fuel cap to ensure it is securely fastened and free from damage, as a faulty cap can allow gas vapors to escape. Utilizing a diagnostic scanner can help you uncover any error codes related to the fuel system or emissions components, providing further insight into potential issues. Pay special attention to the evaporative emissions system, inspecting the charcoal canister and purge valve for any signs of wear or leaks. Additionally, examine the exhaust system for cracks or damaged gaskets that could contribute to the gas smell. Finally, monitor the engine's performance for any irregularities, such as rough idling or decreased fuel efficiency, which may indicate an underlying problem. By following these steps, you can effectively diagnose the source of the gas smell and take the necessary actions to resolve it.

What could be causing a gas smell in my 2012 Mercedes-Benz S350?

When you detect a gas smell in your 2012 Mercedes-Benz S350, it’s crucial to understand the common problems that could be responsible for this alarming issue. One of the primary culprits is a fuel leak, which can occur in various parts of the fuel system, including fuel injectors, lines, or the fuel tank itself. This not only poses a significant safety risk but also requires immediate attention to prevent potential fire hazards. Another common issue could be a faulty fuel cap; if it’s loose or damaged, it can allow fuel vapors to escape, leading to that unmistakable gas odor. Additionally, problems within the exhaust system, such as leaks or a malfunctioning catalytic converter, can also contribute to the smell, as they may allow unburned fuel to enter the cabin. The evaporative emissions system, designed to manage fuel vapors, can also be a source of the problem if components like the charcoal canister or purge valve are malfunctioning. Lastly, an engine misfire, often caused by faulty spark plugs or fuel injectors, can lead to incomplete combustion and a noticeable gas smell. Given the potential safety implications, it’s advisable to have your vehicle inspected by a qualified mechanic to accurately diagnose and resolve the issue.

How urgent is it to address the gas smell in my 2012 Mercedes-Benz S350?

Addressing a gas smell in your 2012 Mercedes-Benz S350 is not just a minor inconvenience; it is a pressing safety concern that requires immediate attention. Ignoring this issue can lead to severe consequences, including the risk of fire or explosion due to gasoline leaks, especially if there are ignition sources nearby. Furthermore, the health implications of inhaling gasoline fumes are significant, with symptoms ranging from dizziness and headaches to more serious long-term health effects. Additionally, gasoline leaks can have detrimental effects on the environment, potentially contaminating soil and water sources. Therefore, it is imperative to act swiftly and investigate the source of the gas smell to protect your safety, health, and the environment. Taking prompt action can prevent dangerous situations and ensure that your vehicle remains safe to drive.

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