Why does the mileage decrease significantly after a full tank?
2 Answers
If the mileage decreases significantly after a full tank, it may be due to a faulty fuel level sensor or an issue with the airbag light wiring harness. Here is some relevant information: 1. Do not wait until the warning light comes on to refuel: The fuel pump is located in the fuel tank and relies on gasoline for cooling and lubrication. Insufficient fuel can hinder the normal operation of the fuel pump and reduce its service life. 2. It is not recommended to fill the tank completely: Gasoline expands when heated and evaporates into gasoline vapor under high summer temperatures, requiring space to accommodate this. If the tank is filled to the brim without any space, gasoline vapor or even liquid gasoline may enter the carbon canister for storage. When the carbon canister is full, it overflows into the air, which is not only wasteful but also pollutes the environment.
This issue often comes up in car owner groups. There are actually several reasons why the mileage decreases after a full tank. First, when the tank is full, there might be air bubbles or inaccurate sensor readings, causing the computer to initially overestimate the mileage, but the truth comes out as soon as you start driving. Additionally, changes in driving habits are crucial—for example, feeling more at ease after refueling and pressing the accelerator harder, frequent braking in traffic jams, or turning the AC higher can instantly increase fuel consumption. It's recommended to start with the basics: check if the tire pressure meets the standard, as low tire pressure increases friction and affects mileage. Also, avoid too many cold starts, as the engine is less efficient then. Regularly cleaning the air filter can also help the car 'breathe' better and maintain stable fuel consumption. Finally, record the actual mileage and fuel consumption a few times instead of relying solely on the car's display, which often gets it wrong.
