2011 Ford F450 Super Duty Crew Cab Diesel Supplement 5th Printing - Page 26

Maintenance and Specifications WARNING: The fuel system may be under pressure. If the fuel filler cap is venting vapor or if you hear a hissing sound, wait until it stops before completely removing the fuel filler cap. Otherwise, fuel may spray out and injure you or others. WARNING: If you do not use the proper fuel filler cap, excessive pressure or vacuum in the fuel tank may damage the fuel system or cause the fuel cap to disengage in a collision, which may result in possible personal injury. Selective Catalytic Reduction (SCR) System Your vehicle is equipped with a selective catalytic reduction (SCR) system to help reduce emission levels of oxides of nitrogen from the exhaust of the diesel engine. The system automatically injects diesel exhaust fluid (DEF) into the exhaust system to enable proper SCR function. Importance of maintaining the DEF level In order for the SCR system to operate properly, the DEF level must be maintained. Generally, the DEF tank should be filled during the oil change service interval. See the scheduled maintenance information in this supplement for more information. However, certain conditions or driving styles, such as trailer towing or fast rates of acceleration, will require the refilling of the DEF tank more often. The engine control unit will monitor the amount of fluid available in the DEF tank. Running a system check in the message center will indicate whether the DEF level is ok or if it is less than 1/2 full. A message will automatically be displayed in the message center when the DEF level is low and needs to be refilled. When you see this message you should refill your tank. See Message center in the Instrument Cluster chapter of your Owner's Guide for message center functions. For instructions on refilling your DEF tank, see Filling the DEF tank later in this section. 26 2011 Diesel (eco) Supplement, 5th Printing USA (fus)