The AAA warns that many inaccessible car parts, such as door locks, window regulators, wiring harnesses and climate control units are difficult to clean and dry and may fail after being contaminated by dirty water. You can look for the presence of dried mud in crevices of the car, and for mud, dirt and debris under carpeting and mats. You should open the trunk for a visual inspection and the smell test. If it is musty, it may be flood-damaged. Flex some wires under the dash to see if they bend or crack.
Wet wires become brittle when they dry, and they can crack and fail at any time.
Inspect the trunk, glove compartment, and under the seats and dashboard for signs of mud, rust or water damage. Look for discolored, faded or stained upholstery and carpeting. Carpeting that has been replaced may fit too loosely or may not match the interior color. Check for a visible watermark line indicating that the car was partially submerged, and for musty odors resulting from mildew. But don't just rely on your own personal inspection.