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Fumes in my car

Several weeks ago I had the speed sensor replaced in my transmission. As I was driving away from the dealership I started to feel a burning sensation in my mouth, throat and lungs. By the time I got home I was coughing and my sinuses were irritated. Several hours later at home I was OK but it happened again the next day so I took it back to the dealership. They said that they saw some transmission fluid on the muffler but that it would burn off and I would be fine. 3 weeks later I am still suffering and it seems to be getting worse even with the windows partly open. I don’t smell any kind of odor or smell, I just get this burning sensation in my mouth every time I get in the car - I don’t have to run the AC or fan for it to affect me - and am wondering if it might be something else, like anti freeze, or another kind of fluid. Is there some detection device I can buy to figure out what chemicals are coming out of the vents?

There are such detectors. I’ve attached a catalog from one company, however there are others and I’d suggest a Google search for fume detectors.

Any shop that does emissions testing should be able to detect fumes including gas fumes.

A return to the shop to check it again for a leak can’t hurt.

@dognostrils I believe this shop wasn’t too interested in driving your car long enough to verify your complaint

transmission fluid on the exhaust won’t cause any of your symptoms

You probably have a fuel or an exhaust leak

Take your car to a different shop. Perhaps the next mechanic will have a better approach.

Well it could be almost anything, but let’s for sake of argument say it happened as a result of fixing the speed sensor. Xmission fluid could well leak doing that job, and xmission fluid dripping on the exhaust pipe can make a pretty good stink. Esp if it is an auto xmission. Is it an auto? That’s the only thing I can think of, assuming it is related to replacing the speed sensor. It may be there’s a seal that was damaged in the process and needs replacing, or was replaced and not done correctly, resulting in a leak. Sometimes there’s a special seal installing tool needed to do it correctly, and a shop doesn’t have that specific tool, so they’ll improvise and a leak could result. But if that’s the case the leak should be easy to see, so take it back again and ask if they see any new-looking leaks.

@GeorgeSanJose I’ve driven plenty of vehicles with oil and/or ATF leaking onto the exhaust and burning off. You don’t get OP’s symptoms from that

Exhaust leak or fuel leak can most definitely cause OP’s symptoms. I’ve fixed cars that were essentially undriveable because of fuel and/or exhaust leaks.

I so appreciate everyone’s help with this! Update: I had the engine cleaned and the undercarriage washed and took it back to the dealership today. They used a blow torch to get all of the baked on transmission fluid off the muffler. I insisted that they drive the car around for at least 15 minutes to see if they had any reaction similar to mine but they didn’t so I was thinking that this might be fixed. I drove downtown tonight for a class and the burning in my mouth (and now on my lips) returned with a vengeance WITH THE WINDOWS DOWN ! Go figure ! Tomorrow I’m going to take my car in for an anti freeze pressure check to see if there are any leaks there and to check for a fuel leak - this makes sense since the taste in my mouth has such an alcohol-y kind of taste - the same sensation I get if I happen to get a good whiff of gasoline. I’ve gotten some return emails about devices I can buy to test the CO and fuel levels so that will be my next MO and will keep you posted. Thanks again.


I will say it again:


Find another shop that will properly diagnose and repair your car.

I wonder what the explanation will turn out to be? Why did this occur immediately after replacing the speed sensor? The speed sensor shouldn’t have anything to do with the fuel or exhaust systems. Maybe it will turn out to be a coincidence is all. Something else in the fuel or exhaust system was about to go haywire anyway and it just happened at the same time the speed sensor was repaired.

It’s a toughie. I think the idea posted above about using an emissions sniffer to find the source of the leak may be what’s needed to do the diagnoses. Best of luck to the OP.

Info for GeorgeSanJose - When I took it to the dealership I also had an oil change, they replaced the air filter, and topped off all the other fluids as well as vacuumed out my car and cleaned my windows. They recommended that I have my serpentine belt replaced, although the other two shops I took it to said it looked fine, and to have the bracket replaced and tightened. At first I thought the reaction I was having could have been related to some solvent they might have used to clean grease off the carpet or headliner but because this has become worse rather than better I don’t think that’s the case. I had a pressure test today at another shop to see if it had an anti freeze leak and it did not. They also checked for gasoline leaks, didn’t see or smell any and no exhaust leaks. I asked my next door neighbor if she would ride around with me to see what she thought, and I didn’t describe any of my reactions to not influence her. After about 5 minutes she said her sinuses were burning and she felt a strange sensation on her tongue. I was happy to know that I wasn’t going crazy! She suggested I get a respirator mask at Home Depot to wear just so I wouldn’t get sick while I’m figuring this out. I got one advertised for paint fumes and one for household cleaner fumes like bleach and solvents. I wore one for about an hour while I drove to my class tonight and the other on the way home but I still had the burning and weird minty taste in my mouth. This is so strange - I have never experienced anything like this in a car before. There is no evidence that anything is leaking at least not while it’s parked in my garage. I’ll be ordering the fume tester tomorrow.


How did that other shop verify that there are no gasoline or exhaust leaks?

They told me that if there was a gasoline leak they would be able to smell it and see it as the pressure in that system is pretty high. As far as an exhaust leak, not sure, this was a shop that did muffler repair but also did other repairs, tune ups, AC service, etc.


The proper way to check for exhaust leaks is to use an evap/smoke machine. It will find even those leaks that are not extremely loud and obvious.

Sadly, there are still some mechanics out there who aren’t very familiar with these machines.

Similar story, my work 2003 ford truck, similar problem, ended up a TSB about particles on head gasket caused a drip of oil, right onto the exhaust manifold. It was tolerable around town but had to do a road trip for a conference, windows open all the way! Being a truck I figured would not be too bad, but it would have been. Connoitered an alternative to displace oildrip, it does not have to be a big leak to make your life miserable.

If your vehicle has a cabin air filter, have that filter changed. It does the same job as a furnace filter. I used to notice an odor in a vehicle after it was serviced in a shop. If the fumes from the garage permeated the air filter, you will smell these fumes every time you run the heater or air conditioning system.
Sometimes, obvious things are overlooked. Perhaps a mechanic left a grease rag under the seat. Check the interior thoroughly. Also, sniff the steering wheel and other places a mechanic may have touched the car with greasy fingers and used some kind of solvent to remove the grease.

One of the shops I took it to is a transmission repair shop but also does other repairs and they recommended that also and printed out a “how to” for doing that for a Jeep. Thought I would at least purchase one this weekend and let my son undertake that project when he’s home later this summer. I might try to steam clean the carpet this weekend to see if that does anything…

I think you really need to check for a leak of something somewhere, Valve cover gaskets are the first most probable suspect.

Something that I think might be mentionable, I had been in the car with the windows closed but tonight I cracked the windows and could feel the cool air come in around my feet as well as the the strong sensation in my mouth. What could be coming in through down there?

Not that I find them pleasant, but I personally don’t have a reaction like you describe to gasoline fumes or exhaust fumes;l but I do have something similar when I’m exposed to amonia fumes and some other cleaning solvents, like Windex. So it is possible this has nothing to do with the engine compartment, just that some cleaning agent they used remains inside the passenger compartment and is outgassing.

I expect the sol’n to this problem will be straightforward once the source is diagnosed. The potential sources will have to be eliminated on by one I expect.

The interiors of cars are designed so that they are pretty much sealed off from any outside fumes as long as all the windows are closed, the AC and heater is off, ventilation fans are off, and all the vents are closed. So one experiment you could try, while the car is parked and the engine is off in the driveway say, open all the windows, maybe hold an electric fan in one window to blow fresh air in one side and out the other, to completely ventilate the passenger compartment as best you can, then close all the windows, & drive the car with the passenger compartment all closed up as described above for a few miles. Do you still notice the symptoms? If you don’t notice the burning senstion then, that would imply the fumes are coming from outside the passenger compartment. If you still notice them, then they must be coming from inside the passenger compartment. At least you’d have something to go on.

I assume you made sure that they didn’t leave an air freshener under the seat?