The contact owns a 2024 Toyota Highlander. The contact stated there was an abnormal fuel odor inside the vehicle's cabin coming from the rear of the vehicle near the fuel tank. No warning light illuminated. The vehicle was taken to the dealer where it was diagnosed that the vent valve remained open causing fuel to leak from the fuel tank and as a result the fuel cap needed to be replaced. The vehicle was repaired however the failure persisted. The failure was intermittent. The contact stated that the odor was extremely strong, causing the driver to sustain headaches. The fire department issued a letter with a statement that there was a fume odor coming from the vehicle. The vehicle was taken to a different unknown dealer however, the dealer was unable to determine the cause of the failure. The vehicle was not repaired for the most recent failure. The manufacturer was made aware of the failure. The failure mileage was 2,000.