GMC Terrain: Performance and Maintenance / Diesel Exhaust Fluid

Diesel Exhaust Fluid (DEF) is used with diesel engines to reduce the amount of regulated emissions produced. The DEF system must be maintained for the vehicle to run properly. It is normal to hear the DEF system purge fluid back into the tank after the vehicle is shut off.

Locating Diesel Exhaust Fluid

DEF can be purchased at a GMC dealer. It can also be purchased at authorized vehicle dealerships. Additionally, some diesel fueling stations or retailers may have DEF. For vehicles with an active OnStar service plan, OnStar can help to locate a DEF retailer. See Customer Assistance Offices for phone numbers to assist you in contacting a GM dealer. See Recommended Fluids and Lubricants.

As the DEF tank becomes low on fluid, warnings begin with approximately 1 600 km (1,000 mi) of remaining range. These warnings will increase in intensity as the tank becomes empty. Once the tank is empty, the vehicle speed will be limited. If there is an issue with the quality of the fluid or the exhaust fluid system, warnings will be displayed in the Driver Information Center (DIC). See Diesel Exhaust Fluid.