What is wrong with my 1999 Buick Park Avenue door lock?

take the door panel off and inspect the locking rods in the door to make sure they are not fouled up if they are not try spraying some wd-40 on the lock mechanism from the back while the panel is off then try spraying some in the key slot it's self last resort take it to the dealer

When you get door open spray some lubricant on the door catch mechanism on the door itself. give that a try. If that doesn't do it try some graphite in the lock. If that doesn't work it's time to remove door panel and see what's going on. Use some wd40 or liquid wrench available at walmart or auto parts store.

if the problem is the lock mechanisim wont move then something is pinched inside or one of the rods from the lock is bent preventing it from unlocking. instead it just bends when you try to unlock it. take the door panel off and you will have to just look and see how it works and figure out if something looks out of place or jamed.

extra suitable than possibly the Idle Air administration Valve (IAC) is caught in the closed place. this may well be a mechanical failure of the IAC or a wiring or PCM project. The broker tech might desire to be able to variety this out easily whether that's a relentless symptom.