Hello everyone,

I almost always drove my 2015 Altima with windows closed & recirculation on but after I started getting sick I took my CO meter with me in my car and one day I noticed that while I was driving with the AC on low, recirculation mode on and windows fully closed the meter showed 14 PPM (Parts per million) carbon monoxide level, I noticed this while going up a hill on a toll-road while the engine was working hard to keep up the speed up the hill. I then immediately opened the window and the CO level dropped to zero within a few seconds which means the CO meter was working properly.

I later found out that if you have AC on low, recirculation mode on and fully closed windows, the carbon monoxide levels would go up to about 6PPM and would quickly rise to >14PPM within 10 minutes of doing any sort of aggressive driving like what is required sometimes to go on an on-ramp in traffic, up a hill, stuff like that.

The type of carbon monoxide meter I used was a Industrial Scientific T40 Rattler.

Anyone else experience something similar or have any ideas?

Yes, I mean, sort of. In that it's happening in my car now, but I don't have a nice meter to verify it. I just smell it. I'd like a meter, I wonder what numbers I'd get. Maybe I'll buy one! Anyway, the climate intake vents are near the windshield wipers on my car. The engine bay let's heat and air exhaust in the same place behind the hood. I don't know that recirculation makes a perfect seal and figure some air is still sucked in from outside and that is bringing in the exhaust with it. So, as a starting point, you can inspect your exhaust system, primarily the components in the engine bay. Maybe take off whatever trim pieces and heat shields are around the manifold and cat and such. Look for black exhaust marks coming out near a gasket, bolts or oxygen sensor. Look at all sides and use a mirror if you need to. My leak is a crack in my oem cast exhaust manifold. I have not had it repaired/ replaced yet.

My car is new and under warranty, had several dealers look at it and they have no idea what's causing it.

This is the CO meter I used:
https://www.durawear.com/t40-rattler-co ... -18105254/

Yeah, I looked at the meters. Out of price range for a curious person. Pretty good price for someone who'd use one regularly.

A muffler shop could eliminate the exhaust leak option. If the dealership isn't putting it up on the rack and pulling off each heat shield and doing a thorough inspection, then they aren't taking the issue seriously. CO is poison. Having a car poison it's driver under warranty is ludicrous imho. Having no idea of the cause is no reason to stop looking.

I thought it was just me. I smell every time I get out of my car. I plan to buy a meter and take my car to a dealer very soon. Thank you all for posting about this topic.

This just seems messed up to me.

Welcome to NICO Club BigCity! let us know what happens please, and if you get a meter, what numbers you get.

If car has a belly cover under motor you might remove it to stir up the air there. Look at any flex section they have in the exhaust pipe and often behind engine.The way they work means they can leak easily.

As said recirc often is not airtight at the duct door and can still pull some cowl inducted air in, and the windshield base being a high pressure point will often pull some air off a leaking rear hood seal to induct leaking exhaust into the a/c.

Start car stone cold, you can often hear a slight exhaust manifold leak until the engine swells up parts enough from heat to then get quieter. Shoving a shop towel into the tailpipe opening can often make a leak further forward show up too.

I bet these cars still have some leftover 'flowthrough ventilation' too, if you can turn everything HVAC off but still feel some air moving through your vents, you can possibly get CO in through wherever those entry ports are as well with the windows closed.

BigCity,
PM me, I can help you with the way I tested mine.

Hi, when I drive faster my altima 08, I can smell a little bit like something is burning, more like plastic burning, it would be something related to this?

Well, exhaust leaks smell like exhaust, not plastic, at least according to my nose. It's also poisonous and will make you feel light headed and nauseous. A combination of some oil and coolant on the engine (a dirty engine) can make a sort of plastic smell when heated up nice and hot. Also, there is plastic under the hood and that could actually be the source of the smell. Doesn't your engine have like a giant plastic cover over the top? Maybe some of that is touching your exhaust pipes. Look around the exhaust stuff for some plastic touching. Then, look around the oil pan and belts side of the engine for a build up of grunge.

Well, as you probably know if you own an Altima,it has the ability to put the back seats down from within the inside of the car for extra storage space in the trunk. Apparently I found out that when you do that, the levels of CO (Especially with recirculation ON) can increase up to ~200PPM!!! So it makes sense that if the CO is coming from a problem in the trunk then even with the seats up some of it would still make it through because after all the back seats aren't air-tight, its just cloth & material.

If the trunk lid either does not pull up close or damage to a seal to it then air drafting under car and up the back will enter into the low pressure at back of car to come in. Carrying exhaust with it. Had a AMC Hornet once that did that, I had to readjust the hatchback lid to tighter to stop it. The seal was not touching to seal at the back, car had been wrecked and I had to do some creative hatch opening edge flange movement to pull the seal up close where it was not due to the compromised opening. I had a rear main seal leak that actually filled the car up with visible smoke starting in the back, it all went away with those moves and fixing the seal leak in combo.

Hi AMC,
Thanks for the interesting information but just to be clear I'm not referring to just my car in my last post. As far as I know my car was in PERFECT MINT condition (No accidents or anything like that) and I've borrowed a few cars to see if it's just my car that include years of 2013 through 2017 Altimas from the dealers and one of my friend's too and they've ALL had this issue then the other day I found this link when searching for "carbon monoxide Nissan Altima" on Bing.com search the other day:

https://lawyer4lawsuit.com/lawsuits/nis ... ma-lawsuit