There are no known hacks for your model, however you ca try the following:
Try here:
Unlock Kenwood DVD playersor
"These codes are applicable for all Kenwood
radios that do not have DVD or DVD screens located on unit.
Your radio will require one of the following procedures.
Type 1
During the code request mode, while holding the DISP key depressed, press and hold the Volume UP or DOWN key for 3 seconds
(so that “…” disappears).
Then using your remote enter your code.
Type 2
Press the "Auto" button and "Track up" on face of radio at the same time. The four dash lines ( . . . . ) should "disappear".
Then using your remote enter your code.
Type 3
Model# DPX-4020 and DPX-4030
Press and hold the 1 then the 6 preset key (preset keys are the buttons on face of radio for storing you "favorite" radio
stations). "C" should display.
Then using your remote, enter your code.
Enter your number from the
remote control unit. Your code number is 5227 (KCAR)
* Press numeric key “5” ( 2 times ) and press the Track UP/Next Track key on the
remote * Press numeric key “2” ( 3 times ) and press the Track UP/Next Track key on the remote
* Press numeric key “2” ( 1 time ) and press the Track UP/Next Track key on the remote
* Press numeric key “7” ( 2 times ) and press the Track UP/Next Track key on the remote
The
security is canceled and the set enters the TUNER mode!"
From
Kenwood CD Unlock Code