When it is time to replace the battery in your door/window sensor, you will see an alert on your system panel.
The DSC PG9303 door/window sensor requires a 3-volt lithium CR2450 Panasonic battery, which can be purchased at your local hardware, mass retailer, or battery store.
1. Locate the sensor with a low battery on either your system panel.
2. Bypass the sensor on your panel.
3. Open the cover by inserting a coin into the slot, then twist to remove it. If a coin is not available, insert a 4mm flat screwdriver into each slot of the plastic cover, then twist to open each side.
4. Remove and replace the 3-volt lithium CR2450 Panasonic battery.
5. Make sure the area where the batteries are stored is clean and there is no corrosion.
6. Place the cover back on starting with the opposite end from which it was opened. You should hear a snapping sound if it closes correctly.
7. Arm and disarm the system to clear the bypassed sensor.
8. Check if the low battery status has cleared.