Refuelling and tending to a diesel engine can cause confusion among uninformed or inexperienced users. In addition to accidentally refilling the fuel tank with gasoline instead of diesel, some motorists may mistakenly put the Diesel Exhaust Fluid (DEF) into the fuel tank, which can affect the performance of the fuel pump module, or lead to more serious problems.
On its Techlink service site, GM has outlined steps to follow for diesel car or truck drivers that mistakenly add DEF into their vehicle’s fuel tank. The first thing to know is that if diesel fuel is mixed with DEF, or if DEF or gasoline is added to the fuel tank, it may lead to repairs that will not be covered by GM’s factory New Vehicle Limited Warranty.
Major repairs can be avoided if the ignition is not turned on, the engine is not started and the vehicle is not driven. In scenarios where the in-tank fuel pump has not been run, the fuel fill pipe, tank and fuel pump module should be replaced. If the fuel pump has been run but the engine has not been cranked, the system from the fuel fill pipe to the high-pressure fuel pump, as well as the high-pressure pipe from the pump to the rail, must be replaced along with the low-pressure return lines.
In scenarios where the engine has been cranked, the entire fuel system from the fuel fill pipe to the high-pressure fuel pump, fuel rail, injectors, injector return fuel lines, high-pressure fuel pipes and low-pressure return lines must be replaced. A fuel pump module that has been contaminated with DEF may show corrosion of certain steel and aluminum components, a crystal-like residue on the module’s exterior or fractured/damaged terminals.
GM also notes that if DEF was added to the fuel tank, the vehicle should not be driven to the dealership for service. Additionally, the vehicle ignition should not be turned on and the vehicle should not be started.
“These actions will help limit any damage to the fuel system from contaminated fuel,” the automaker says. “The New Vehicle Limited Warranty may not cover any fuel system repairs related to fuel contamination.”
Some GM models that are available with diesel engines and may experience DEF contamination include the GMC Savana and Chevrolet Express utility vans, GMC Sierra and Chevy Silverado full-size trucks and its line of full-size SUVs like the GMC Yukon and Yukon XL and Chevy Tahoe and Suburban.