The fuel evaporative emission control system is designed to be able to store the hydrocarbons rising from the sealed fuel tank (evaporation) to prevent unburned gases from polluting the atmosphere. It consists of a charcoal vapour storage canister, check or purge valves, and interconnecting vapour lines. The canister is usually found in the engine compartment or under the wheelwell trim and it is important to check for damage and leaks in the canister and vapor lines at least once every 24,000 miles (38,600 km). Any old or cracked hoses should be repaired or replaced and the canister replaced if it is cracked or damaged. Aside from checking for damage, there is no need to do periodic maintenance on this system.