Car key remote control no longer works

In most cases the key's coin cell battery is flat – this is the most common cause and is easy to fix yourself. Open the key housing with a small screwdriver or a coin (see the owner's manual for instructions), note the battery type (often CR2032 or CR2025), and buy a replacement at any pharmacy or electronics store. After replacing the battery, the key sometimes needs to be re-paired: insert it into the ignition and turn it once or twice. If that doesn't help, the electronics may be faulty – in that case, take it to a workshop.