Said It Here

Why is there a bad smell coming from my car vents?

Moisture and debris trapped in the air conditioning system or cabin filter create a foul, musty odor that lingers when the vehicle is turned off. This makes starting the car an unpleasant experience even though the smell often fades once you start driving.

What people tried

Every workaround mentioned in the threads below. We haven’t tested any of them — and nobody here is claiming they worked.

  1. 1
    Replacing the cabin air filter
  2. 2
    Spraying Lysol into the passenger footwell area with climate control on full hot and recirculation
  3. 3
    Checking the evaporator drain tube for clogs
  4. 4
    Driving the car until the smell goes away or until getting used to it

In their words

Unedited, grouped by where they were said, most upvoted first within each place, each linked to the thread it came from.

r/MechanicAdvice1 person · September 2026

“the moment she got it back it had a strong BO smell. I figured it would go away but it’s been a few weeks and the stench has not left.”source ↗

“We replaced the cabin air filter and the smell is still there, it is coming from the vents, anyone know how to get rid of this??”source ↗

ayyitsthekid · r/MechanicAdvice · 1 upvotes
r/AskMechanics1 person · September 2026

“for the past few days ive noticed that the car smells like something rotten or a bad fart when I first enter the car but the smell quickly goes away when driving.”source ↗

“The smell is NOT there during the drive but only after the car has been off for some time.”source ↗

Extension_Copy_9737 · r/AskMechanics

Where this came up

People with this problem also raised