An overnight putrid/foul odor appeared in a 2002 Civic. Can’t find a single culprit. Any ideas on what it could be and what to do about it?
Saturated charcoal canister
rotting leaf or other debris in vents (below windshield)
Dead mouse in heater duct (these miserable #%$^&@ can crawl through a hole 1/4 their size!)
Perhaps just a mean fart that didn’t get vented. (eye roll)
I go with the dead mouse in vent theory. This is common enough. The remedy requires disassembling the vent system – a time-consuming task.
Step 1 in the diagnosis. Determine if the smell is stronger with the HVAC on or the HVAC off.