DTC 45: Processing In 20-Second Lock-Out: Description
WARNING: This page is about a different car, the 2002 Pontiac Firebird and 2002 Chevrolet Camaro. However, it is still accessible from the selected car via links, so may be relevant.
At least 50 consecutive digital Radio Frequency (RF) messages were received from a remote transmitter that is programmed to Body Control Module (BCM), but message did not pass encryption security test. BCM will cease processing any remote transmitter digital RF messages for 20 seconds. No remote function capabilities will exist.
DTC 45 will set when remote transmitter has been in program or synchronize mode while out of range of BCM. Fault may also exist if remote transmitter is defective. Fault could be induced prior to BCM entering diagnostic mode. Most likely cause is that remote transmitter is out of synchronization with BCM.