I have a 2003 Honda Civic 4-door sedan that did not come with “remote entry.” (I bought the car “Certified Used” in 2006.) For the past six months or so, my driver’s side door lock has been very sticky and oftentimes I cannot even get the key into the lock. Othertimes, I can get the key in, but the lock doesn’t rotate at all. A few months back I had routine maintenance at the dealer and mentioned the problem and they put a little WD-40 in to “loosen it up,” which helped for a few weeks, but then the problem returned. Any suggestions?
WD40 is the wrong lube to use on locks and key cylinders.
Try a spray of graphite that goes in wet and dries without leaving a residue to collect dirt.
However, this may also be temporary, IF the lock mechanism is worn out, in which case it will need replacing.
Not having a remote lock system means the key and locks will be worn out sooner.