I took my Fit into the dealer today because my key was sticking in the driver's side door. They replaced the key lock cylinder again but said water was getting in behind the door panel. They could not find the source of the leak. They did not really offer any permanent solution. Has anyone else had this problem?

 

How long does a cylinder last?
How many miles/years?

How old is the car?

That's not the answer.

It's supposed to do that.
ALL car doors with movable windows allow water inside the doors.
They are designed to allow water to flow through the inside of the door....thus the drain holes along the bottom inside edge so they don't fill with water.

That's not the problem with the lock.

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The door lock does wear its tumbler wafers as it is used... the key wears too.

Most people that have keyless entry (remotes) don't wear out the door lock cylinders as they never stick the key in the door lock.

I would just replace the tumblers in the lock if the cylinder wasn't damaged, that's still quite a bit of labor to do the work but at least you wouldn't need multiple keys for the same car.
If the key is worn, it too needs replaced along with the lock tumblers overhaul..

The tumblers in the ignition lock cylinder can also suffer the same wear issues eventually.

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I'd tell a driver to lube the locks with graphite....
Honda loads the locks with a thin grease they call 'permalube', that's what I use when I retumble locks.


HTH