It's a common problem with Passlock II (the theft deterrent system your car is equiped with).
The 'trick' you found is about the only thing you can do about it before you start replacing parts.
Here is the official GM passlock relearn procedure:
-turn key like you're going to start the car
-let key back to run
-wait until the security light goes out (about 10 minutes)
-turn key to OFF for 5 seconds.
-Start the same procedure again (starting at the first step) for another two times (three relearns total).
On the third time when you turn the key off and turn it back to start, your car should relearn the passcode.
In your case one relearn is enough, but just in case I figure I'd tell you that sometimes three relearns are necessary.
Now. At some point, this relearn procedure won't be enough to start your car (I can't tell you when. My wife has been driving her 2003 impala with the same problem for two years; it only happen to her once every other month or so). At this point you will probably have to take you car to a dealer to have it checked. Repairs may include new passlock sensor, new ignition switch/lock cylinder, new IPC, new BCM.
Hope this help a little bit.
I feel your pain. Every impala drivers do :(
Sunday, December 14th, 2008 AT 4:34 PM