How can I eliminate a bad smell from my Fiat 500?

I bought a January 2009 Fiat 500 and have had it for nearly four months. However, recently there has been a bad smell inside. It is not a petrol or oil smell. Could the cause be attributed to the cold, wet weather or could it be something more serious, in which case a trip to the dealership would be the best option? My warranty runs out in January.
Might be a dead mouse or bird trapped inside the ventilation system somewhere. It's worth opening the bonnet and taking a look. It might be a damp and mouldy pollen filter, because the vent well drains are blocked. It’s also worth feeling under the floormats for damp in the underfelt, signifying a leak, but if the car was leaking it would also suffer severe condensation on winter mornings. If the smell is from bacteria in the heating and ventilation trunking, run the heater at maximum for 10 minutes and that should kill the bacteria. Alternatively use a can of Autogym Air-Con Sanitizer, £11.95 from accessory shops.
Answered by Honest John on

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