Exhaust in passenger compartment (High CO levels)

[NHMS3]

So, as the title says, I've been getting a whiff of exhaust in the cabin, especially in the morning. This has happened since I got the car around 9200 miles, prompting me to buy a CO monitor to make sure I'm not going to be fumigated. I highly recommend doing this if you have any suspicion that you have an exhaust leak as it could save your life.

I took the car in at 12k for service, and the tech at the dealer "wasn't able to replicate the problem" and sent me on my merry way. I continued to monitor CO levels, now with some 26k miles, and found that this week every day the CO went over 20ppm on my drive to work. Not enough to kill you, but enough to make you feel a little funny. Friday the CO level shot up to 111 as I merged onto the freeway. For those that don't know, this is approaching a level of CO that could cause you to pass out, not ideal for driving.

I called and made an appointment at the dealer and they've got the car and stuck me in 2011 Mazda5 for the time being. The car is under warranty, so the fix should be payed for by Mazda. My question for all of you, is: Where do you think the leak is? Block and manifold? Manifold and turbo, turbo and downpipe, downpipe and 2nd cat? 2nd Cat and exhaust?

That it happens more when it's cold has me leaning towards a flat gasket junction rather than the flex joints at the 2nd cat, but what do you think?

Car is a 08.5 MS3 Sport.

 

[rmgedon69]

My guess would be the connection from turbo to dp. And since the fresh air collector ducting is pretty close to that vicinity...the CO that you are monitoring is coming from the air vents.
Regardless where the leak is coming from, hopely your dealership can locate the source of the problem.

 

[NHMS3]

The CO is definitely from the air vents. if I put the air on recirculate, I don't get as much, but on a longer highway drive, it will still pull in enough air from outside to get a reading >9.

 

[NHMS3]

Well, heard from the dealership this morning:

They are not able to replicate any exhaust leak on a test drive, but believe any odors may be coming from the cabin air filter which needs to be replaced.

I've re-iterated that the issue is not a smell, but a measurable and alarming level of CO inside the car under normal driving conditions. They initially questioned my measurement method, but have stated that they will have their tech contact the Mazda tech helpline...

Any further advice?

 

[oaklandopen]

Cabin filters? Is the carbon monoxide coming from decomposing bugs in the filter? Lowl. Or is it dioxide that comes from decomposition....can't remember

The tech is probably just driving around and sniffing for themselves. Maybe his sniffer is busted

Next time request a ride-along, with your tool. You won't want to be driving, and the tech won't want you driving either. There is nothing worse than a customer holding a tech hostage while insisting there is a problem when the tech doesn't see it, and driving around till it happens

The other thing they should be doing is a smoke tes. If you have a leak of some sort, this will find it

Id suggest you do it yourself, but I can't think of a cheap enough way to do it if you don't get the machine. Maybe you could rent it

Essentially, you hook it up via the spark plug port (might have to pick and choose till you find a cyl stuck at the exhaust stroke), then blow smoke in it. Eventually smoke will come out of the back of the exhaust, and anyplace else that there is an opening

Hope that helps