Bexley Auto Repair

Yes, a loose, cracked, or incorrectly sealed gas cap can trigger the check engine warning light. The fuel cap is part of the evaporative emissions control system, commonly called the EVAP system. That system prevents gasoline vapors from escaping into the atmosphere and directs them back into the engine to be burned. When the vehicle tests the EVAP system and detects that it cannot hold the expected pressure or vacuum, the engine computer stores a fault code and may turn on the warning light. A loose gas cap is one possible cause, but it is not the only one. Hoses, valves, seals, sensors, and the fuel tank can produce the same type of leak. How The Gas Cap Seals The Fuel System The gas cap closes the fuel filler neck and seals fuel vapors inside the EVAP system. Most caps use a rubber gasket that presses against the filler neck when the cap is tightened. Some modern vehicles use a capless filler system with spring-loaded internal doors instead of a removable cap. D ... read more