A vehicle can be a big investment so it is important to make sure that no one can take your car without your keys. Nowadays, almost all vehicles have inbuilt immobilizer systems which prevent the engine from starting unless the correct key is being used.
Early systems had a simple code stored on the key which was read by the computer while trying to start the engine. Now, more advanced methods of encryption are used, so it is much harder to trick the system these days. The overall idea is the same though, whenever you turn the key, the car’s computer reads a code from the key and checks it against the codes that are currently known. If the computer finds a match, it will let you start the engine.
If a key match is not detected, a few things can happen. The engine may start and run for a few seconds before dying or the engine may not even turn over at all. A warning light is included on the dash to let you know how the system is reacting.
What the immobilizer warning light means
The indicator for the immobilizers behave similarly between different vehicles, but refer to the owner’s manual for specific information on your vehicle’s system. Generally, when you first start the engine, this light will illuminate for a few seconds showing that the correct key has been used. If the computer doesn’t recognize the code on the key, the light will flash multiple times. You won’t be able to start the engine until you use a recognized key.
If you have a keyless ignition in your vehicle, make sure that the key is close enough to register with the receiver inside the car. Even if the key fob has low or no battery power, most vehicles have a backup procedure so that you can still start the car. Information on this procedure will be included in the owner’s manual.
All vehicles can have multiple codes registered at a time so that you can have multiple keys to use the car. A factory scan tool or an already known key is needed to teach the car new codes.
Is it safe to drive with the immobilizer warning light on?
This warning light usually only comes on when the key isn’t recognized so you shouldn’t have to worry about this light coming on while you are already driving. If this happens, try taking the key out and reinserting it if you are having trouble getting your car started. If you are experiencing any troubles, check and verify that the key fob isn’t out of power.
If your car’s immobilizer system isn’t working properly, our certified technicians can help you diagnose any issues you are encountering.
This article originally appeared on YourMechanic.com as What Do the Immobilizer Warning Lights Mean? and was authored by Spencer Cates.