2018 Toyota Highlander Smells Like Gas

Address Gas Smells in Your 2018 Toyota Highlander Safely

Find Repair Location
Reviewed by
Bo Fader
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 Toyota Highlander 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 Toyota Highlander 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.

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 2018 Toyota Highlander?

When faced with a gas smell in your 2018 Toyota Highlander, it's essential to adopt a systematic diagnostic approach to identify the root cause effectively. Start by inspecting the fuel system for any visible leaks, focusing on components like fuel lines, injectors, and the fuel tank. A common and straightforward issue could be a faulty fuel cap; ensure it is securely tightened and free from damage, as a loose cap can allow gas vapors to escape. Next, utilize a diagnostic scanner to check for any error codes that may indicate problems within the fuel system or emissions components. Pay particular attention to the evaporative emissions system, examining the charcoal canister and purge valve for signs of wear or leaks. Additionally, inspect the exhaust system for any cracks or damaged gaskets that could contribute to the gas smell. Finally, monitor your engine's performance for any irregularities, such as rough idling or decreased fuel efficiency, which may signal underlying issues. By following this structured approach, you can effectively narrow down the potential causes of the gas smell and take the necessary steps to resolve the issue.

What could be causing a gas smell in my 2018 Toyota Highlander?

If you're detecting a gas smell in your 2018 Toyota Highlander, it's crucial to understand the common problems that could be at play. One of the primary culprits is a fuel leak, which can occur anywhere in the fuel system, from the tank to the injectors, and poses a significant safety risk. Inspecting the fuel lines and connections for any signs of leakage is a good starting point. Another potential issue could be a faulty fuel injector, which may not seal properly, allowing fuel to escape and create an odor. Additionally, the evaporative emissions system, designed to prevent fuel vapors from escaping into the atmosphere, can develop leaks that lead to noticeable gas smells inside the vehicle. A simple check of the fuel cap is also advisable; if it's loose or damaged, it can allow vapors to escape. Lastly, don’t overlook the exhaust system, as leaks or malfunctions in components like the catalytic converter can sometimes produce a gas-like odor. If you identify any of these issues during your inspection, addressing them promptly is essential for both safety and vehicle performance.

How urgent is it to address a gas smell in a 2018 Toyota Highlander?

Addressing a gas smell in your 2018 Toyota Highlander is not just a matter of convenience; it is an urgent safety concern that should never be overlooked. Gas leaks can indicate serious issues within the fuel system, which, if left unaddressed, could lead to dangerous fire hazards. Moreover, inhaling gas fumes poses significant health risks, including dizziness, headaches, and nausea, which can impair your ability to drive safely. Ignoring this warning sign can also result in further damage to your vehicle, leading to more extensive and costly repairs down the line. Therefore, if you detect a gas smell, it is imperative to act quickly by consulting a professional mechanic who can accurately diagnose and resolve the issue, ensuring both your safety and the longevity of your vehicle.

You’ve got options with RepairPal

Whether you need a more accurate auto repair estimate or help finding a reputable shop in your area, we’ve got you covered.