5 Symptoms of Engine Immobilizer Problems

A car immobilizer system is a common anti-theft feature in most vehicles produced in the past 20 years or so. When it works like it’s supposed to, it greatly reduces the chances of your car getting stolen.

When problems arise with your car immobilizer, it can cause major headaches. Keep reading to understand how an engine immobilizer works, signs of a malfunction, and how to fix it

symptoms of bad car immobilizer.

What Is an Engine Immobilizer?

An engine immobilizer system (or car immobilizer) is a great piece of electronic security technology which is basically a vehicle theft deterrent.

Its purpose is to prevent a vehicle from being hot-wired and stolen by a thief who doesn’t have a key to start the engine. Research studies have proven there are 40% fewer car thefts since immobilizers were introduced into cars.

If you’ve purchased a car that was made within the last 20 years, then you’ve probably already used this technology without even realizing it.

The car keys that car dealerships distribute now are basically key fobs or smart keys. That is why the base of the key contains buttons to lock and unlock car doors, open the trunk, or sometimes even remotely start the vehicle.

Many key fobs on newer vehicles don’t even have a physical key attached to the base. You just have to be inside the vehicle with the key fob in order to start the car by way of an Engine Start button.

Lost or Damaged Key Fob?
Before paying an arm and leg at the dealership, be sure to check out CarAndTruckRemotes.com for a replacement key fob at a fraction of the price.

Main Components

An engine immobilizer system is a security feature that prevents unauthorized access to your car’s engine. It consists of several key components:

Transponder Key or Smart Key – A transponder key or smart key is a special key that contains a microchip. When you insert the key into the ignition, the microchip communicates with your car’s engine control unit (ECU) and sends a unique code. If the code matches, the engine starts. If not, the engine remains immobilized.

Key Fob – A key fob is a device that may double as your transponder key and allows you to lock and unlock your car doors remotely. It uses a battery to function properly, and if it runs out of power or gets lost, you may face problems with your car’s security system.

Immobilizer Module – An immobilizer module is the main brain that communicates with the transponder in your key. It is connected to various sensors and an antenna that helps send and receive signals between your key and the vehicle.

Engine Control Unit – Your car’s engine control unit (ECU) receives signals from the immobilizer module and activates the ignition system if the correct code from the key is received. This collaboration between the immobilizer and the ECU plays a key (pun intended) role in keeping your car secure.

Warning Light – The warning light on your dashboard is an indicator that illuminates when there’s a problem with the immobilizer system. If everything is working right, the light should disappear after a couple of seconds when you turn on the ignition. If it stays lit or starts blinking, there might be an issue with the system.

Car Alarm – A car alarm is often integrated with an engine immobilizer to alert you and others nearby if someone is trying to break into or tamper with your vehicle. It helps add an extra layer of security to your car.

Physical Key – Even though electronic keys have become quite popular, many vehicles still provide a physical key as a backup to unlock your doors or start your vehicle in case of electronic key failure. Don’t forget the importance of your physical key!

How Does a Car Immobilizer Work?

engine immobilizer problems

The inside of the key fob contains a transponder chip. When you put the key into the ignition or have the key fob inside the vehicle (for keyless fobs), the transponder chip inside the key fob sends a security code to the car’s immobilizer system.

If this security code matches the code in the immobilizer system, the car will be allowed to start. If the key is not legitimate or there is no key fob or transponder present, the car will not start.

This security code is random each time you start the vehicle and your key is the only source that can generate the correct token for the vehicle.

The good news is that this this electronic immobilization system works very well in preventing car theft and getting your key stuck in the ignition is a thing of the past.

The bad news is that if you lose your key fob or the transponder chip is damaged or goes bad, you’ll need to get a new key from the auto dealership which can be very costly.

Top 5 Symptoms of an Engine Immobilizer System Malfunction

Like anything else that is electronic, an immobilizer system can malfunction and case some problems for you. Here are the 5 most common signs that you can expect to experience if there’s a problem somewhere in your car’s immobilizer system.

#1 – Unlocking Problems

car won't unlock

When you use your key to attempt to unlock the doors of your vehicle remotely, the doors don’t unlock. Unfortunately, many modern-day vehicles don’t have keyholes on the outside of the doors, so you cannot open them manually with your key.

This means if you lock the doors from the inside and then close the doors, you won’t be able to get back into your car because your key won’t be able to unlock the doors. At this point, you’d have to call a locksmith to unlock the door.

#2 – Locking Problems

Similar to the last symptom, you probably won’t be able to lock your doors with your smart key if you cannot unlock them either.

Without a working smart key or key fob, the only way you can lock your doors is if you lock them from the inside as the doors are open and then you close the doors. The problem with this is that you risk the chance of leaving your car keys in the vehicle with no way to get them out.

#3 – Engine Does Not Start

cylinder misfire causes

A common symptom of a problem with your engine immobilizer is that your vehicle does not start at all. If it weren’t for the problems with the locking mechanisms, there could be a wide variety of reasons why your engine does not start.

But if you experience those problems and have an engine that doesn’t make an attempt to start, then you clearly have a problem with either your immobilizer or the smart key itself.

See Also: Car Starts But Then Dies? Here’s Why

#4 – Key in Ignition Does Not Turn

If your key fob has a physical key that you must insert into the ignition and turn and it doesn’t budge, you may have a problem with the transponder chip inside the key fob base. For some reason it’s not sending the security code to the car immobilizer.

This is often due to water damage (water + electronics don’t mix) or actual breakage of of the chip due to the fob falling or being crushed.

Before ordering a replacement key, make sure you’re using the correct key fob for the car. Just because your spouse drives the same make of car doesn’t mean her key fob will work in yours.

#5 – Car Alarm Problems

car alarm problems

Since the immobilizer is the main security feature of your vehicle, that means your factory car alarm system won’t work if the immobilizer is faulty.

See Also: Why is My Car Alarm Going Off Randomly?

How to Fix

bad transponder key symptoms

Many immobilizer problems can be fixed simply by simply replacing the battery in the key fob. Many transponder keys depend on a small battery to relay the security code to the car immobilizer. Be careful replacing the battery so you don’t accidentally damage the transponder chip inside.

If you’ve replaced the battery and it still doesn’t work, you may have some type of damage to the transponder chip. In this case, you will have to contact your local car dealership and request a new key.

They are not cheap to replace so be prepared to shell out a hundred or even a few hundred dollars for a new key. Usually, the more expensive the vehicle, the more a replacement key fob will cost.

If the actual immobilizer system in the vehicle is to blame, then it could be due to the wires being corroded or damaged. Perhaps the engine control unit or its sensors are malfunctioning or faulty.

These situations would require you to go to a car dealership or auto repair shop that specializes in electronics for further troubleshooting.


How Do I Know If My Immobilizer Is Working Properly?

You can check if your immobilizer is working properly by observing your car’s behavior when you start it or when the key is inside the ignition.

If your immobilizer is functioning correctly, you should be able to start your car without any issues. However, if you notice problems starting your car or if the immobilizer warning light on your dashboard comes on, you may have an issue with the system.

Where Is the Immobilizer Located?

Your car’s immobilizer is usually located within the ignition system or the key fob, which contains a transponder chip. This chip communicates with your car’s immobilizer system to allow the engine to start when the correct key is used.

Keep in mind that the specific location of the immobilizer may vary depending on your car’s make and model.

Why Does the Immobilizer Light Keep Blinking?

If the immobilizer light on your dashboard keeps blinking, it’s likely indicating an issue with your immobilizer system or your transponder key. This might mean that the system is not recognizing your key or that there is a problem with the immobilizer itself.

In order to resolve this issue, you may need to replace the key fob, reprogram the transponder key, or consult a professional mechanic for a thorough examination of your immobilizer system.


Mark Stevens


  1. Please I noticed recently whenever the car is hot under the sun, it won’t start….not even cranking. On the dashboard it shows immobilizer active.

    In the mornings or when it gets cold, it starts. I have changed the key battery. The key locks and unlock the car very well. The vehicle is a Volkswagen passat 2007

  2. Hi, I have a 2013 Mazda 3 with a key fob. After turning off the engine once I got home, the immobilizer light went on and keeps on blinking. Tried to lock/unlock the car but still keeps on blinking. Even started the engine which it did and the immobilizer light went away. But after turning off the engine, the light went on again and blinks. Put a new battery on the key fob as suggested on online. Started it again, light went away and went on again after turning off the engine. What could be the problem?
    Thanks, Jong

  3. Hi ive got some issue on my corolla altis 2004. After i turned my key to start up, the engine light won’t come out and i can’t start my car. Sometimes in the morning the light come on after i turned my key on n able to start. Is it cause of the immobilizer error?. I need some advice cause that’s my daily car. Thanks in advance.

  4. had a problem with my ford transit custom mk8 immobilizer malfunction any way i can disable that one other option the dealer cost unaffordable for me
    Thanks, Richard

    1. Have you tried changing the battery in your key? What exactly are the problems you are having with the immobilizer?

  5. My car Chery Arizona 5 2023 immobilizer is not working at all we have replaced the immobilizer coil , ECU and the BCM but still it isn’t starting.

  6. My vw passat 2007 immobiliser activates when it’s left in the hot sun.Key works on doors etc.. Dealer says its the steering column, please advice.

    1. Why does the dealer suspect the steering column? I’m reading that this is a somewhat common issue among early 2000s Volkswagens that can be caused by a bad ignition switch or a bad connection to the instrument cluster.

  7. Good day sir, I have a Corolla Altis 2006 model, while changing the battery in the key fob, the chip got damaged and unaware I inserted the key in the ignition trying to start the vehicle but the vehicle won’t start and the theft alarm goes on continuous, I invited a locksmith to take a look and read the codes but it won’t communicate with the scanner, that was when we noticed that the immobilizer light is off and not blinking at all, please what could be wrong and what should I check for?

  8. I have a 2012 Nissan Murano the air conditioning went out this summer so the condition the condenser and pulley were bad which in turn took out my tensioner pulley so I replaced both of those and I’ve replaced my starter and I replaced four serpentine belts because it kept chewing up belts I replaced the battery I replaced the a fusible link to the battery. Now it won’t start doesn’t even crank over to start it I replaced the battery in the key fob but I don’t know what to do next

    1. I don’t know. I guess I would check the ignition and the immobilizer. Probably the best thing to do is to go in and have them scan the immobilizer to see if there’s any problems recognizing the key. If not, the shop should be able to diagnose the problem or at least help you with next steps.

      1. Hello,
        I recently bought a Toyota wish 2012 model. The immobilizer light on the dashboard keeps lighting when I switch off the engine. But the car starts well and the light goes off while I am driving. Should I be worried?

  9. My jetta4 1.6 it doesn’t respond to the immobilize key for opening n closing n the windows doesn’t open manually

  10. Son lost his key to his 2006 Nissan x trail, got a replacement, not from a dealer. The car arrested and he drove it. After parking it he returned a few minutes later and it turns over but won’t start. Any thoughts?

  11. I have a 2010 Ford F150. I had the key reprogrammed because my antitheft was because the truck’s engine would turnover but would not start. I attempted to start my truck and the antitheft light is back on and the truck still does not start. Any suggestions of what my problem could be now?

  12. I only have a key with a chip on it no key fob with batteries or anything like that. Out of the blue my car won’t start and a warning symbol comes up in the dash. Google says it means my car immobilizer has an issue. The ignition won’t even turn over. Ignition is locked. Whats the fix with a microchipp3d key with no key fob

  13. Hello .I have a nissan micra 2006 .if I put the key and on ignition the mobilizer light wont go off and the car wont.what start. .what could be the problem?

  14. I have a 2007 camry. When removing the dash to fix my ac The immobilizer cracked and the car won’t start. I have a donor car (2005) that I could use the immobilized from. How should I go about reprogramming? Tks

  15. The Immobiliser on my Kia Rio failed three months ago. The entire system was replaced (at my cost) and the car starts and drives. But! The auto-transmission does not change gears. It operates in top gear only. How can this confidence trick even EXIST without the provider’s responsibility to repair/replace faulty items?
    The motoring world has been hijacked and no government seems to be able to prevent this dishonest institutionalised fraud. Are their any REAL pro-motorist associations who might help, anywhere in the world?

  16. I lost my FOB/key to my 2008 Passat Wagon, I took it to a locksmith who has replaced and programmed a key for me which worked great. I lost the only key that I have and now the locksmith said that they can’t order and program a key for it, they told me to have it towed to a VW dealer which I did. The VW dealer service dept. called to tell me that they haven’t been able to reprogram the new key that I ordered from them. Basically, the car can’t be repaired and may be totaled. I can’t believe that this can’t be remedied. The dealer told me it could cost up to 6 or 7K to repair it, clearly the car isn’t worth that much. Any ideas? Black market repair?

  17. Dear man…
    For few weeks i have a problem with my immobilizer on cold-morning. (Winter).
    The car is Jeep WJ …. (No batteries in keys).
    We placed our two keys but the problem exist .
    I even try to tie (with a strip) one key to the immobilizer-antennae itself… No Help.
    Only my wife hair-drier, for a minute or two solving our problem.
    …Can you leave me your advice please.

  18. Hi I have a 2003 holden rodeo, I’m thinking it’s the immobilizer as the engine light flashes and won’t crank, I’ve seen alot of posts that say it was a early issue with these and were recalled my question is can I disable the immobilizer and will this sort it? Or will I need new keys etc?

    1. Unlikely you’ll be able to disable the immobilizer without other consequences. When was the last time the key batteries were replaced?

  19. I have a vauxhall astra and i changed the battery yesterday and now id does not start and immobiliser light came on. Will a reset of both systems, car and key fix the issue. I have car locksmith coming who says he can solve it


  20. Hello! Cant seem to get anywhere, wondered if you had any thoughts, my scoda Fabia 2012 has immobiliser fault on dashboard and only starts 50% off the time. The other times the engine turns over and then immediately cuts out. I know if it won’t start because I also can’t open the car windows. I usually have to keep re inserting my key until the windows work and I know it will start again. Been going on for months now. My spare key does the same so it’s not a faulty key. Thanks!

    1. Could be a problem with the ignition, perhaps? Or maybe the keys have batteries and both have died at roughly the same time? I’m not sure, we don’t have Škodas here in the US.

  21. Hello! I have a Peugeot 206 sport -05, and it won´t start, it cranks and it has a spark I think but dies instantly before really start completely. No sound from the fuel pump, so I put in a new one, but still no sound from it, the power reaches the pump. I tried to start for a couple of seconds and then with the key still inside the ignition opened the door and there is a warning sound, someone told me this was an indicator connected to the immobiliser, unfortunately not as if that was to rule a problem with it out or in. No messages inikating a problem with the immobiliser shows. How do I know if the immobiliser is the problem or if the problem is elsewhere? Please help!

    1. If I would try to change the key battery, how exactly do I do that without getting in trouble with the immobiliser if that is not the issue?

  22. I have a 2012. Ram.it randomly shuts off going down the road, but not all the time. I have to pull over to the side of road and disconnect the battery post then reconnect battery. Than get back inside and start truck. It always restarts after this. Do you have any thoughts as to what may be my problem.

    1. It’s probably not the immobilizer, I can tell you that. The immobilizer is an anti-theft system that prevents the vehicle from starting, but won’t shut it off while it’s already running. Sounds like you have a poor connection to the battery, possibly the alternator. Clean the battery posts and battery terminals, see if that improves things. Do a visual inspection of major wiring in the charging system. Do you notice anything that looks out of place?

  23. Hi i have 2010 VW Passat, i have noticed that with the hot sun in Florida when i park my car in the parking lot and close from work for the day the car never starts but just keep popping up ‘immobilizer active’ every time i put my key in to start the car. It could keep bringing that warning signal for like an hour before it finally starts. It doesn’t do this in the morning when heading to work. Do you have ant suggestions on this?

    1. Not sure. Sounds like there may be a bad connection to the immobilizer somewhere. When was the last time the fob battery was replaced?

    2. I have a 2013 VW CC and am currently having the same problem with the immobilization active message coming on where the car won’t start but only intermittently, usually after the car sits out in the hot sun all day. It starts in the morning and at night. The VW dealers haven’t been able to determine the fault codes and haven’t fixed the problem.

      Please let me know if you ever fixed your problem with your car and who fixed it.

  24. I have a Honda Accord 08 model the key light keep blinking on the dashboard, it doesn’t start easily.after starting and driving on motion the engine stop and the key start blinking on the dashboard again.plz I need your help?

  25. 1998 Camry. Purchased with a 40k Japan engine. No key fob or chipped key. Car ran fine. A few days later won’t start. Starter Cranks but no attempt to fire. No fire with starter fluid. Battery good. But also tried with jumpers. Fuses all appear good. All electronics seem to work fine on battery power. Suggestions?

    1. Do you have any codes? Sounds like there may be an issue reading the crank or camshaft sensor signal. That or something else could be up with the timing.

  26. Hi Sean, I have a 2008 Toyota Tundra. I had an issue one time with it. When I tried starting it, it would start then die. It did this 3 times. I sat there, swearing, and then tried again and it started fine and ran. I took it to my mechanic and they ran the codes and said it was the key immobilzer. However, they can’t get it to repeat what happened to me. The cost is $1,200 to replace. Eeek! Can I just disconnect it? The battery on my fob is maybe a year and a half old. I have no problems locking or unlocking the door. Help!!!

  27. I have a Mazda3 2004, I have the original key but lost the immobilizer, it doesn’t crank or start, it’s been sitting for 3 years, last time I parked it it was starting, I only had a cooling system problem

  28. Hi Sean,

    Thank you! I don’t know nor have the manual as I bought it used and it didn’t come with it. With your expertise, whos the best and most affordable to remove it as I don’t want to get gauged at a dealership?

    I appreciate your response and advisement!

    Thank you!

    1. I don’t know. You’ll have to do a little research around your local area to see which shops have great reviews. Agreed that your dollar will stretch further at an independent shop.

      1. I have a 06 ford fiesta light come on dash and it won’t start it not the starter immobiliser promble

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