Whenever the temperature is below 20 degrees F and am idling at a stop light, if I have the heater fan running I get a horrible exhaust smell inside my car. I have discovered that I can lessen the bad smell by turning off the fans when the car is idling and then turning it back on when I start to drive. Any ideas of what I should do to fix it?
You need to find out where the leak is. Could be exhaust manifold or manifold gasket…or where the manifold connects up to the exhaust.
This is actually common…in the cold the exhaust gasses are more prone to hang around at ground level… Ever notice how much steam seems to come out of your tailpipe? Well you heater fan is sucking these vapors into your car thru the cowl of your car. I dont THINK you have an exhaust leak but I could be wrong…you would have to tell us that. If you have no leaks then it IS quite possible that the cold air is keeping those vapors around or near door level…which makes it very easy to suck that air into your cabin…when it warms up those vapors are far more likely to rise up and away from you…
Do you hear the exhaust leaking? Is it louder than before or does it sound “Farty”
You need to find the leak. This is an unsafe condition. If you’re getting a strong exhaust smell in the car you have a leak, and that means you’re also getting carbon monoxide in the car. CO can put you to sleep while driving without your realizing it.
This is NOT normmal. In over 40 years of car ownership, driving in all kinds of weather including regularly driving in subzero weather, I’ve never had or smelled an exhaust smell in a passenger cabin that was not due to either an exhaust leak or oil leaking onto a hot exjaust manifold. Do not assume this is normal. It is not.