Most people choose an invisible fence when they want to keep their pets in a confined area, but don't need the privacy or security that comes with traditional fencing. An invisible fence is less expensive than traditional fences because you don't have to buy materials or hire someone to build the fence. However, if your invisible fence stops working, you may have to call the company to troubleshoot; that can be expensive. Try troubleshooting problems with your invisible fence yourself.
Check the pet collar first. Your pet may be getting out because the transmitter collar batteries are dead. Check the fit of the pet collar; some pets can remove their collars with a little pulling or chewing. If the pet collar isn't tight enough, your pet may not be registering the electrical shock.
Adjust the electrical shock that your pet receives if your unit allows. Perhaps it is too low and the animal is just not registering it.
Check for a break in the underground wiring of the invisible fence. Most invisible fence units register an error if there is a break in the fence. It should either flash red lights or set off an alarm. Remove the ends of the fence wire from the transmitter jacks and replace them with the ends of a spare piece of wire. The wire doesn't have to be any special type, but will work best if it's near the gauge of the wiring used in the invisible fence. The idea is to mimic the invisible fence's circuit to make sure the error indicator is registering a fence break. If the error indicator keeps going when you complete the circuit with the spare wire, there may be a short in the transmitter. If the error indicator stops when you complete the circuit with the spare wire, it means that there is a break in the underground wiring.
Check the underground wiring for an actual break in the invisible fence. Buy an RF choke, an inexpensive radio part available at any electronics store. The RF choke has two leads that should be placed into the transmitter jacks. Then take the two fence wires you originally removed from those jacks and twist each one around the other ends of the RF choke leads. The fence wires should be attached to the leads close to where they join the coils. Tune a portable radio to the frequency your invisible fence uses. You will know you have the right frequency when you hear fast tapping or beeping through the radio. Walk the perimeter of the invisible fence and look for drops in the signal. These indicate breaks in the wiring.
Contact the company that installed your invisible fence if none of these steps solved your problems. It may be a short in the transmitter unit, or it may be defective.