Cabin Air Duct Odor Repair

Vehicle: 2013 Lexus 300h

Since my wife purchased her car, we have noticed it has an odor when the cabin air is on. Best description I can give is that is smells like old gym clothes… not good at all. I’ve read up that it’s likely mold of some sort and had her take it in for an assessment from the dealer. their response was as follows

“Regarding the odor the tech is recommending that a charcoal cabin filter be replaced and perform a mist service, which will sanitize and deodorize the heating and air conditioning ducts. This is a service item and the selling dealer may not have experienced this condition during the inspection. I can perform these two items if want to move forward.
The fee to do so would be $275.00 plus tax or you can contact the selling dealer to see if any assistance can be given”

So my questions…
1.) Is the price reasonable?

2.) How difficult is this for a DIY? I’ve done a lot of DIY for both our cars, but haven’t replaced any cabin filters yet. Are there any specific things to be extra careful with were I to undertake the task myself? (any tips?)

3.) Does this sound like something we can argue the dealer that sold the car to handle without a fee? We only got this car in mid-late March. So not a lot of time has past since then.

Thanks for your comments.

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Great question, and a problem that I have heard many ask. I want to see what the experienced mechanics at the group have to say. I solved this myself on my Lexus IS with a disinfectant spray into the cabin air inlets (not to be confused with engine air intake), but I am not suggesting you do it. I also found that if I ran the heat for a while it helped a lot. I did that with the car in the shade on its own, as opposed to while I was in it. I had the AC button “on”, but I am not sure that made any difference. My understanding is that there is only one cabin air filter in most cars and that it is an easy DIY swap. Through the glove box. I have done that on all my cars. Those with more understanding may know more about that.

Usually cabin air filters are extremely easy to replace. My wifes 07 Lexus ES350 takes me less then 2 minutes. I’d be surprised if your Lexus 300h takes more then that.

If you’ve never replaced the filter then I’d start there. If it’s real dirty, then I suspect that’s all you’ll need done.

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By any chance, is your car a Certified Pre-owned Vehicle from Lexus? AKA Lexus L-Certified. If it is not, is it still under the 4-year comprehensive warranty (4 years, 50K)? If it is covered by either, you should ask the manager of any Lexus dealer why this is not covered.

Cabin air filters are NOT covered under warranty.


A few years ago my 2013 Equinox smelled like something died in the duct work. There were the remains of a mouse nest on top of my cabin air filter. I replaced the filter. To remove the smell I sprayed a can of Lysol into the windshield cowl/grill with the cabin fan at the max setting and the windows open. After that it was fine, but I make sure to check/replace the filter yearly.


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There are probably more cabin filter replacement videos on YouTube then a person could count.

Here’s how to replace the cabin air filter.

Then what you want to do is reinstall the filter frame without the new filter, and spray this product into the system

Then remove the filter frame, and install the new filter, and put everything back together.



Well, I’ll suggest it, 'cause that’s a good solution!

The owner’s manual should tell how to replace it. It’s not hard on that car. Replace it and see if the smell goes away. If it doesn’t, remove the cabin filter, close the access door again, then run the air conditioner on high and spray a bunch of Lysol into the intake vent below the windshield. Then switch to high heat and do the same thing. Finally, turn on the defroster and do it again. This will get the disinfectant into all of the plumbing.

Now replace the filter, which you removed to make it easier for the Lysol to get into the vents.

Your car will smell like Lysol for awhile, but that’s better than the musty stuff and the smell will fade with time.

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@MikeInNH makes a good point. The cabin air filter would not be under any Lexus warranty. However, in the case of this post, the car is less than 3 months from having been purchased. Worth asking if it is covered under the warranty if any, or if the dealer would like to correct it gratis. Lexus did a lot of that for me during my years of under-warranty ownership. They even filled my tank any time they did warranty work. Cabin air filters are inexpensive, but $275 to correct the problem is pricey.

Here are the instructions from my Wife’s Lexus ES-350 owners manual on how to replace the cabin air filter.

“See your Local Lexus Dealer.”

Thanks for the great feedback. I thought it might be an easy solution. I’ll go ahead with the DIY on this one and will do the suggestion mentioned by Tester.

Thanks again.

Fortunately they were not so asinine for the 2013 300h. It’s on page 708. :wink:

I think people were getting a little pissed at manufacturers for saying go to the dealer for simple jobs like this. Years ago the owners manual use to obtain information on how to change your oil and sparkplugs.

For the 2007 Lexus ES350 the instructions for replacing the cabin air filter are on page 311 of the owners manual.

OP should just look in the owner’s manual.

…and if the appropriate info is not found in the Owner’s Manual, there is a decent chance that the instructions can be found inside the box containing the replacement filter.

My Outback takes the same cabin air filter as some Toyota models, and the box for the replacement filter always has an instruction sheet detailing how to replace it on those Toyota models. The filter mfr does not provide instructions relating to Subarus, but–luckily–that info can be found in my Owner’s Manual.

I can vouch for @Tester s fix. I did the same with a product to remove the foul smell of cigarette smoke from my Mustang. It took two tries but it worked.

I sure hope it’s just a dirty cabin air filter, and not fungus on the evaporator core

another thing . . . if your car has an “afterblow” function, make sure it’s activated

I believe lysol, ozium, etc. just combats the symptoms, not the actual cause

This topic came up on an episode on the Car Talk radio show recently, OP might want to give that show a listen to see what Ray and Tom had to say. As I recall, the fellow who phoned in had a problem with weeds sprouting & growing from the air inlets./ He pulled them out, but the roots were still inside and rotting, creating an odor.

I was thinking while listening to Tom and Ray discuss this topic, that what really makes sense is to somehow back flush the fresh air inlet system. I wonder if it might be possible to hook up a Shop Vac in blower mode to the heater vent, and reverse-blow that stuff out the air inlets under the windshield?

That’s how I clean the coils on my refridgerator btw. And it works really well, much better than trying to vacuum them off. It does create a huge mess in the kitchen tho, debris from the fridge coils shoots out & blows everywhere !! :slight_smile: