Ford Mystique Owner's Manual page 82

Replacement/additional transmitters
In the event a transmitter is lost, return the remaining
transmitters to your dealer for reprogramming of your remote
entry system. This is necessary to prevent further unauthorized
use of the lost transmitter.
Additional transmitters may be purchased from your dealer
(remote entry system will work with up to four transmitters).
Return your existing transmitters to your dealer so the remote
entry system can be reprogrammed with your new and existing
transmitters.
THIS DEVICE COMPLIES WITH PART 15 OF THE FCC
RULES. OPERATION IS SUBJECT TO THE FOLLOWING
TWO CONDITIONS: (1) THIS DEVICE MAY NOT CAUSE
HARMFUL INTERFERENCE, AND (2) THIS DEVICE MUST
ACCEPT ANY INTERFERENCE RECEIVED, INCLUDING
INTERFERENCE THAT MAY CAUSE UNDESIRED
OPERATION.
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