The key lock is a plain mechanical barrel. It is separate from the central locking, so a stiff or frozen barrel is a different job to a central locking fault. See Central locking faults if the fob side is the problem.
How it works
One owner who studied it says the barrel is on the outside of the glass and the latch is on the inside. Turning the key puts the barrel in a position to push on a set of rods, which wind their way round the window guide and operate the door latch. When the barrel is in the locked position, pressing it with your thumb doesn't push the rods. Central locking uses a different point on the lock, so the key can't override it. See Central locking and alarm: what your car has.
Stiff or won't turn
- Spray WD40 right into the keyhole using the straw that comes with the can (one owner's suggestion). It didn't help the owner with the failed barrel below.
- Try the spare key. One owner found it behaved the same, which pointed at the barrel and not the key.
- One owner suggested holding the lever open while working the key, to take pressure off the mechanism. That didn't help when the barrel was stuck locked, as there is then no pressure on it.
- A barrel that works some of the time and sticks at others may be worn: one owner who needs to wiggle his key blamed the barrel or key.
Frozen locks
When the whole barrel freezes it makes no difference whether it is locked or not: you can't push it. One owner makes a lock cover to keep out the weather, and puts de-icer or anti-freeze inside the cover before fitting it over the lock.
- The cover: split a piece of hose pipe down the side (standard hose isn't wide enough to wrap the lock, so it needs patching so there are no gaps), then glue on a circle of hose pipe as a lid. It fits snugly. He painted it with waterproof silver paint, which seals small gaps and stops it standing out on the parked car.
- He only has one, on the driver's door. "As long as that opens, that's enough."
Removing the barrel
Owners disagree on how hard this is.
- 2011: the workshop manual was found next to useless. The owner took off the teardrop-shaped cover on the inside rear edge of the door and could see the lock mechanism, but not enough to remove it. He concluded the only way was to strip the whole door and remove the window. Another owner said there are about three almost impossible to reach nuts and bolts, and a third thought the door cards and window would have to come out.
- 2014: a later owner says you can remove the barrel without taking off the door card, in about five minutes: take off the teardrop cover, remove one plastic bit of linkage, remove two 10 mm bolts and slide out the barrel. This is the most specific report, but he didn't post photos. See Door panel removal if you do need the card off.
A temporary bodge (one owner)
In 2011 one owner's driver's barrel failed in the locked position. The key went in all the way but wouldn't turn the lock. He glued a 10p coin to the back of the barrel with Araldite (he could reach the back through the teardrop cover). That widened it enough that, even in the locked position, it pushed the lever mechanism. The car could still be locked and unlocked with the central locking afterwards. It is a stop-gap and nobody reports how long it lasted.
He had earlier established that the central locking and key lock aren't connected, and the barrel broke while testing. With the roof off he could still open the door from the inside handle.