Diesel Exhaust Fluid Tank

The DEF tank holds the DEF supply. The filler neck has a smaller diameter 19 mm (0.75 in.) than the filler neck of the diesel fuel tank and is fitted with a magnetic insert so that diesel fuel cannot be mistakenly added to the DEF tank. If diesel fuel is added to the DEF tank or DEF is added to the diesel fuel tank, immediately contact an authorized Detroit™ service outlet for further instructions.