The check engine light may illuminate due to an EVAP system fault. Our technicians tell us that the purge valve should be checked for debris or carbon contamination. If contamination is found the purge valve and carbon canister should be replace and the EVAP hoses blown out with compressed air. All EVAP system hoses are subject to cracking and splitting causing leaks. Inspect hoses carefully. Aftermarket gas caps are very prone to failure also.