5 Symptoms of a Bad Engine Immobilizer in Your Car

A car immobilizer does just what the name indicates. It is a technological security device that will prevent your car from moving. In other words, it is an anti-theft device that will prevent thieves from being able to hotwire your car and drive it away.

As you may expect, if you have a faulty immobilizer, it can make your vehicle undriveable. Here’s how an immobilizer works and things you should look for if you suspect immobilizer problems.

See Also: 5 Cars Least Likely to Have Their Catalytic Converter Stolen

How a Car Immobilizer Works

With many modern cars, the only one who will be able to start your vehicle is whoever has the key fob. There is a digital token which gets sent from the key to the immobilizer whenever you attempt to start your vehicle.

If the wrong token is sent or no token at all is used, then your starter motor, ignition, and fuel system will remain disabled by the immobilizer.

This is great news for responsible car owners who want to prevent their cars from being stolen. However, if you lose your car key fob, then you may need to go to the dealership and pay hundreds of dollars for a new one.

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Common Bad Car Immobilizer Symptoms

For the security of your vehicle, the car immobilizer system and the transponder chip in the key BOTH need to function properly. If either one of them wears out or gets damaged, then it could cause a whole array of problems and symptoms.

Below are five common symptoms that you can expect to experience with a bad car immobilizer.

See Also: Symptoms of a Bad Ignition Switch

1) Doors Won’t Unlock

unlock doors with key fob

If you press the unlock button on your car key fob and the car door does not unlock, this is a sign that your key fob is not communicating with the immobilizer system. Perhaps the battery in your key needs to be replaced or the immobilizer system itself is having issues.

Whatever the case may be, your key fob will not be able to transmit properly without a functional key and immobilizer. In the meantime, you will either need to call a locksmith or have your car towed to the dealership so that you can unlock your door again.

2) Doors Won’t Lock

lock car doors

If you cannot unlock your door with a key fob, then you probably won’t be able to lock your door with the key either. This means that you’ll need to either leave your doors unlocked or leave the windows down if the doors automatically lock after a certain period of time.

Until you get the problem fixed, your vehicle will be vulnerable to thieves, vandals, and bad weather if you leave your windows down.

3) Alarm Won’t Function

what sets off car alarm

The alarm system in your vehicle is associated with the same security feature as your immobilizer. If you have a bad immobilizer, then you’ll likely have a bad alarm system too.

Depending on the type of alarm system that you have installed, this means anyone breaking your windows or stepping near your vehicle will no longer cause the alarm to go off.

4) Engine Won’t Start

car hard to start

The immobilizer will normally prevent the engine from starting if the proper security token is not given to it. Sometimes you may be able to lock and unlock your vehicle, but the engine still won’t start.

If there is no other logical explanation or mechanical issue to explain why you’re having engine problems, then it could be associated with the wiring of the immobilizer inside your vehicle.

5) Bad Wiring

car wiring low voltage

If you are having problems with your immobilizer but your key is functioning properly, then you need to physically examine the immobilizer’s wiring inside the vehicle.

If the wiring appears to have damage, wear, and/or corrosion, then this is a clear indication as to why your immobilizer system is not working.

As a result, you will need to have all the wiring replaced. This can only be done at the car dealership where you purchased your vehicle.


13 thoughts on “5 Symptoms of a Bad Engine Immobilizer in Your Car”

  1. Hello my Toyota Kzte 3L can’t perform at reaching its full speed to 180km/h it only reaches 40km/h even if you pushed the acceleration to the floor

  2. My 1999 Daewoo Nubira starts with little hesitation time to time. But after a few minutes driving it it will shut off as of to run out of gas. This happened last night when I first brought it home from auction. Tried to start it and it acted like it was out of gas even though need read full. Today was filling it up and it is full. So why would it continue to shut off Check engine light is on.

  3. My byd S7 2015 key is lost, i brought new one and programed,car doors locking and unlocking normal and all instruments are lighting but engine doesn’t start.
    If is it because of new key the starter motor will recive a signal or not !?

  4. My 2006 town and country van won’t start I noticed the master cyl fluid level sensor was unplugged I plug it in still nothing, I opened the sliding pass door from the inside 2 times and heard a chiro when I got the unlock button on the fob , the alarm has been tampered with a while back I noticed it don’t blink probably ex or son. I’m stranded in the desert between Vegas and Bakersfield.

    • If you’re stranded, you should get help from a local. Have the vehicle towed to a nearby mechanic for them to take a look and they should be able to get you back on the road.


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