2018 GMC Terrain Smells Like Gas

Identifying Potential Causes of Gas Smells in Your 2018 GMC Terrain and How to Address Them

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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
0%
40% chance it's the
Emissions Control System
0%
45% chance it's
Something else
The most common reasons a 2018 GMC Terrain 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 2018 GMC Terrain 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 are the potential causes for a gas smell in a 2018 GMC Terrain, and what diagnostic steps should be taken first?

When you notice a gas smell in your 2018 GMC Terrain, it's essential to take a systematic approach to diagnose the issue effectively. Start by checking the fuel cap, as a loose or damaged cap is a common culprit for gas odors. If the cap is secure, move on to inspecting the fuel system for any leaks, paying close attention to the fuel lines, tank, and injectors, as these areas can often harbor damage that leads to fuel smells. Next, examine the Evaporative Emission Control System (EVAP), which plays a critical role in containing fuel vapors; look for any faults in components like the charcoal canister or purge valve. If these initial checks do not reveal the source of the smell, consider the condition of the fuel injectors, as they can sometimes leak vapors if they are faulty. Finally, inspect the exhaust system for any leaks, as exhaust fumes can infiltrate the cabin and create a gas-like odor. By following this logical sequence of diagnostic steps, you can efficiently pinpoint and address the cause of the gas smell in your vehicle.

What could be causing a gas smell in my 2018 GMC Terrain?

If you notice a gas smell in your 2018 GMC Terrain, it’s crucial to investigate the underlying causes to ensure your safety and the vehicle's performance. One of the most common culprits is a fuel leak, which can occur from various points in the fuel system, such as a damaged fuel injector or a compromised fuel line. Additionally, a faulty fuel cap can lead to gas vapors escaping, so checking its condition and ensuring it is properly secured is a simple first step. Another area to consider is the evaporative emissions system, which is designed to manage gas vapors; any malfunction here could result in noticeable odors. Furthermore, an exhaust system leak, particularly near the catalytic converter or muffler, may also produce a gas-like smell. Lastly, engine performance issues, such as running too rich, can contribute to this problem. For those inclined to DIY, start by inspecting these components, but remember that if the source of the smell remains elusive, consulting a qualified mechanic is advisable to prevent any potential hazards.

How urgent is it to address a gas smell in my 2018 GMC Terrain?

Addressing a gas smell in your 2018 GMC Terrain is of utmost urgency due to the serious safety and health risks involved. Gasoline is not only highly flammable, but a leak in the fuel system can lead to catastrophic consequences, including the risk of fire or explosion. Moreover, inhaling gasoline fumes poses significant health hazards, potentially causing symptoms such as dizziness, headaches, and nausea, which can escalate with prolonged exposure. Beyond immediate safety and health concerns, neglecting a gas smell can result in long-term damage to your vehicle, leading to costly repairs that could have been avoided with timely intervention. Therefore, if you detect a gas smell, it is crucial to take action immediately to protect yourself, your passengers, and your vehicle from potential harm.

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