What happens if unleaded gasoline is added to the def tank by mistake?

Adding unleaded gasoline to the DEF (Diesel Exhaust Fluid) tank can cause significant damage to the vehicle's emissions system. DEF is a solution of urea and deionized water, and gasoline can contaminate it, leading to potential clogs and failures in the selective catalytic reduction (SCR) system. If this mistake occurs, it’s crucial to avoid starting the engine and to have the tank drained and cleaned by a professional mechanic to prevent costly repairs.