(repairs to the fuel tank or filler neck must, therefore, be performed by a professional since the work is critical and may be lethal). Despite the periods when the fuel system has been cleaned and flushed, explosive fumes may be present and even ignite when scaling a tank. If it is disengaged from the vehicle it must not be placed in an area of increased risk of sparks or flame ignition of the fuel fumes. Special care should be taken if there exists natural gas-type appliances in the garage because the pilot light can cause an explosion.