Drain all remaining diesel and ensure the tank is completely empty. Use a high-pressure washer with hot water to rinse the interior, focusing on areas with sludge or residue buildup which often trap odorous compounds.

Open tank hatches and vents, and use industrial fans to circulate fresh air through the tank for several hours. For enclosed tanks, consider using portable air purifiers with activated carbon filters which absorb volatile organic compounds (VOCs) responsible for strong odors.

Apply specialized enzymatic cleaners or biodegradable detergents that can break down organic residues causing persistent odors. Follow product instructions, allowing sufficient contact time before rinsing thoroughly.

For severe odors, use activated carbon or silica gel packs placed inside the tank; these materials naturally adsorb odor molecules and can be replaced once saturated.

Use approved biocides diluted according to specifications, ensuring full coverage of interior surfaces. Let the solution sit for the recommended period before flushing it out completely with clean water.

After cleaning, ensure the tank is completely dry before refilling to avoid bacterial growth. Install breathers with odor-filtering capabilities to reduce external odor infiltration.

Schedule periodic inspections and cleanings to address residue accumulation early. Using fuel stabilizers can minimize fuel degradation, which is a common source of unpleasant odors in stored diesel.