The Sony head unit on your sound system is just the tip of the iceberg of your audio set-up. It houses the human interface components and the audio inputs. Removing the head unit is the first step to any audio set-up upgrade or repair. However, Sony head units are somewhat more complicated to remove than those of other brands, because they require custom keys to unlock the head unit from the DIN. If you do not have the keys, you can shimmy the head unit out with a flathead screwdriver and some patience.
Put your car in park and engage the parking brake so you have a stable car to work on.
Fold the front display of the head unit down first to expose the actual head unit hardware. Pull the display off and place it to the side. Locate the two slots on either side of the head unit; they are right on the seam between the head unit and the centre dash bezel. If you head unit uses a wire key, slide the wire into the right side first and rotate the wire 180 degrees until you hear a click. Then insert the wire key into the left side and rotate the head unit 180 degrees. Pull the wire key out and the head unit will pop out a little. Pull the head unit out by hand. If your head unit uses flat keys, go to Step 3.
Insert the right flat key into the right slot until it clicks in place. Leave the right key in and insert the left flat key into the left slot until it clicks in. The keys both have handles on their ends. Pull the handles and the head unit will come out with the keys. If you have none of the keys, go to Step 4.
Insert a thin, flathead screwdriver -- the thinner the better -- into the right-hand slot. Shimmy the screwdriver along the side of the head unit until it starts to come out on the right side. Repeat the process on the left side until the head unit starts to come out on the left side, too. Once enough of the head unit is exposed, pull it out by hand.
Disconnect the power wire, audio cables and antenna cables from the rear of the head unit before pulling it all the way out.
It's best not do this uninstall at night or in a bad neighbourhood as it will look like you are stealing the radio, especially if you have to resort to the screwdriver method.