“A certain type of spider may weave a web in the evaporative canister vent line and this may cause a restriction of the line,” Mazda said in a letter to the National Highway Traffic Safety Administration.
When the yellow sac spider builds its nest the evaporative canister vent line is blocked, which prevents air from getting into the gas tank as gasoline in used. This results in negative air pressure inside of the tank, which can lead to a crack in the gas tank and the possibility of a fire.
All 20 reported cases of spider infestation have been in cars with 4-cylinder engines. No actual fires caused by the spiders have been reported.
Mazda spokesman Jeremy Barnes also said that the spiders favor model year 2009 and 2010 cars, though it is unclear why since all modern cars have the same type of equipment.
Letters will be mailed to owners of the recalled vehicles beginning at the end of this month. Dealers will inspect the fuel system and repair it if necessary. They will also install a spring to prevent spider intrusion.