Updated: Aug 27, 2019
Strange smell could not be located , so TAKE OUT THE SEATS!
I had trouble locating a smell in this big body Yukon. Did the usual odor killing techniques on this one (steaming the vents, carpet cleaned and shampooed, disinfected the entire interior, but still something lingered in the air. It doesn't happen often, but sometimes you have to resort to stripping the entire vehicle down in order to clean every parts of it; this can mean cleaning the carpet underlayment. Once every seat is pulled out, it is important to pull out the carpet, hosing it down, and hosing down the sub matting to ensure all parts of the interior is thoroughly cleaned.
This is no small task. A job like this can last 2 days depending on how hot the weather is. You need for the temp to be above 87 with lots of humidity. The hot air aids in drying the carpet and the sub carpet as the carpet and sub carpet will be sprayed with hot water and scrubbed. Took a while to get this one done, but once it was stripped down, cleaned, and put back together...no more odors.