Some GM vehicle owners may be tempted to overfill their vehicle fuel tank beyond the automatic shutoff point. However, doing so could result in several engine performance issues and fuel system issues, as explained in a recent report.
Per GM TechLink, if the fuel tank is overfilled beyond three clicks past the automatic fuel nozzle shutoff, it’s possible that liquid fuel may enter the evaporative emissions (evap) system vapor lines. In this scenario, the fuel could block the recirculation line and result in fuel tank pressure sensor readings issues.
With regard to 2019 through 2023 Cadillac XT4 models and 2021 through 2023 Buick Envision models equipped with the turbocharged 2.0L I4 LSY gasoline engine, overfilling the fuel tank may result in illumination of the check engine light, as well as diagnostic trouble code (DTC) P0451 (Fuel Tank Pressure Sensor Performance). To note, these vehicles are equipped with a capless refueling system.
If these conditions are found, GM is recommending that a certified GM technician inspect the three vent lines at the fuel tank for damage and remove any contamination present, as well as drain any fuel from the evap vent lines, if needed. Additionally, the vapor lines connected to the evap canister should be disconnected in order to clear any liquid fuel that may be present in the lines. These lines are accessible by removing the right-hand rear wheel and wheel liner. A GM tech will lightly blow shop air into each line in order to clear it of fuel.
Additionally, GM is recommending that customers be reminded not to overfill the fuel tank. Customers shouldn’t “top off” the tank beyond the automatic shutoff point for the fuel station nozzle in order to avoid overfilling the tank. If the tank is overfilled, it could result in the issues outlined above.
To note, these issues are associated with Bulletin #22-NA-203.