I have had this off and on a few times and always get it around allergy season. First time was last year. I got just tired of smelling it! I read on a few forums that it can be caused by brain tumors, seizures, etc... I am not sure about that as I have no history of either. BUT, I do have a history of allergies! Especially sinusitis. I also have been under a lot of stress since my dad has been sick and have had some acid reflux going on... (another cause of the exhaust smell supposedly) So, after countless searching for what I could do - I laid in bed last night smelling that old familiar exhaust smell... So, I remembered I had some of those breathe right nasal strips... I got one and put it on the bridge of my nose... then, I used saline nasal spray in both nostrils and breathed in very deep! This part may sound gross, but I sprayed enough to taste it. I breathed in deeply a few times and it was 100% better! Today, I am at work wearing a breathe right strip and I don't even care b/c I can breathe and I do not smell the exhaust! Seems like it's something dealing with narrowing passageways in the nasal area or something when there is any type of infection or sinus issues. I'd not rule out other possibilities as I am not a doctor, but this has helped me! Going to try the strips a few days and see how it goes. Good luck to everyone and hope it works for you!
Hello and hope you are doing well.
It could be olfactory hallucinations. Phantosmia most often occurs as a result of a head injury or upper respiratory infection. It can also be caused by temporal lobe seizures, sinusitis, brain tumors, migraine, Parkinson's disease and stroke. You may need proper evaluation by your GP, please consult him for a neurological assessment. He may then refer you to a neurologist if needed.
Hope this helped and do keep us posted.