Why Does My Kitchen Smell of Old Cooking Oil?

A kitchen that smells of old cooking oil is usually telling you something about its exhaust system. This guide lists the common causes in the order worth checking, what your team can do, and when to call a professional. It applies to restaurant kitchens and to homes with a range hood.

Why does the smell happen?

Grease does not only land on the hood. It passes into the filters, the duct and the fan, and old grease gives off a stale cooking-oil smell. When airflow is weak, the smell stays in the kitchen and can drift into the dining area.

What to check, in order

1. The filters. Clogged or greasy filters hold smell and cut airflow. Take them out and clean them: stainless steel baffle filters tolerate hot alkaline degreasers, while aluminium mesh filters need a milder cleaner. Replace any that are bent or no longer seat tightly.
2. The canopy and grease cups. Wipe the inside of the hood and empty the grease cups into a sealed container, not down the drain. Our guide to how to clean a commercial kitchen hood has the steps.
3. The duct. Grease on the duct walls holds smell. Look for grease at the duct access panels. The duct needs machinery to clean properly, so it is a professional job (exhaust duct cleaning).
4. The fan. A noisy or vibrating fan, or grease on the blades or around the roof outlet, points to a fan that needs cleaning (exhaust fan cleaning).
5. The smoke and odour stages. If the kitchen has an ESP or ecology unit or a carbon filter, a dirty collector lets smoke and grease particles through and spent carbon lets cooking odours through. Read what an ecology unit is.
6. Replacement air. An extraction system needs air coming in to replace what it removes. In a tight space without it, the exhaust cannot work properly. That is a design question for a ventilation engineer.

Is it always the exhaust?

No. If the smell stays after the exhaust is clean, check the grease trap and drains, the bins, and any spills under or behind the equipment.

A smell at home: the range hood

Wash the metal filters regularly. If your hood recirculates air instead of venting it outside, it has a carbon filter: check the manufacturer's manual for how often to replace or regenerate it. If you can still smell old oil with clean filters, the duct and fan behind the hood may need cleaning. Our kitchen chimney and range hood cleaning page explains what a home cleaning includes.

When to call a professional

• Grease is visible at the duct access panels
• The fan is noisy or vibrating, or has grease on it
• The smell is still there after the filters are clean
• You cannot remember when the whole system, not just the hood, was last cleaned

We inspect first and recommend only what the system needs, and every job ends with a company-attested report that includes before and after photos and recommendations. For how often a kitchen should be cleaned, read how often to clean a commercial kitchen exhaust.

Kitchen still smells of old oil? Contact HoodEx and we will arrange an inspection. We work day and night shifts, so a visit can be arranged outside your trading hours.

Frequently asked questions