Glossary
DEF (Diesel Exhaust Fluid)
A urea-based fluid required by modern diesel trucks to reduce NOx emissions. Tracked separately from fuel.
DEF (Diesel Exhaust Fluid) is consumed at about 2-3% of fuel volume in modern Class 8 trucks. It's required for emissions compliance — running out triggers limp mode that caps the truck at 5 mph. Most owner-ops fill DEF at the pump alongside diesel, but the cost shows up on fuel-card statements as a separate line. Zenan tracks DEF inline with fuel entries so you can see total fuel-related cost per truck without losing the breakdown.
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