Pontiac 2003 Sunfire Owner's Manual page 74

Resynchronization
Your remote keyless entry system is equipped with a
security system that prevents anyone from recording and
playing back your signal. The transmitter does not
send the same signal twice to the receiver. The receiver
will not respond to a signal that has been sent to it
more than once.
Normally, the transmitter and receiver resynchronize
automatically. However, under certain circumstances,
manual resynchronization may be required.
To resynchronize your transmitter and receiver, follow
these directions:
1. Stand close to your vehicle.
2. Press and hold the LOCK and UNLOCK buttons on
the transmitter at the same time.
3. Hold the buttons for at least 10 seconds. During this
time, the doors should lock and unlock once. This
confirms the resynchronization. If the doors do
not lock and unlock, see your dealer for service.
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