5 Symptoms of Engine Immobilizer Problems


An engine immobilizer system is a common anti-theft feature in most cars 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 and to know what symptoms to look for in case of an engine immobilizer malfunction.

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.

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 – Locking Problems

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

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.

#2 – Unlocking Problems

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

#3 – Engine Does Not Start

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. 

#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

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

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.



  1. My car will crank up an run fine but as soon as I cut it off it won’t start back until the engine is cool down I have a 2003 Nissan Altima 2.5 and I have replaced spark plugs coils packs cam sensor an crank postition and it’s still doing the same thing

        • Not sure if you still need help, but it sounds like injectors to me. I had a much older ford that started having the same issue. it would run fine until I let off the clutch to take off, and then it would die all of a sudden. Cleaned the injectors on a hunch and it ended up fixing the problem, apparently they were spraying enough to keep it running in neutral, but not enough to actually drive the truck.

      • Change your temperature switch sensor. That is the sign of failing temperature switch, It start when the engine is cold and refuse to start when the engine is hot.

    • Gm omg my Chevy Cruze is doing the same thing and now it’s in the shop and I thought it was alternator but the mechanic is saying it has something to do with the key?? I’m so clueless! What happened with yours?

  2. My car is not starting, they have diagnose and they said its mobilizer. It’s crank only not starting. Locking doors and open doors its working.
    Please advise

    • It’s possible since most immobilizers shuts down the fuel pump but still allow spark. Obviously, there are a lot of different reasons for a car cranking but not starting but if “they” have done some basic troubleshooting, the engine immobilizer is definitely a possibility.

      • My 05 acura tsx went into limp mode all of a sudden awhile back with DTC U0107 (can’t communicate with TAC module).. I’ve noticed since this has been plaguing my car that the alarm sets itself like every few mins.. I didn’t even used to carry the key fob part but had to tear my house apart searching for it after driving it home with the alarm blaring (while also going 10mph due to the limp mode)! I’m curious what the connection is with drive by wire issues and this immobilizer system.. Or whatever it is that has caused me to make sure the key fob is immediately accessible even while trying to diagnose my electronic throttle control prob bc I can just move in the seat wrong and the alarm start blaring. I’ve also had trouble getting the car to go out of park & usually have to do the manual override thing with the key to put the car in neutral & then crank it. Any input will be appreciated! Thx!

      • We have a 2009 Chevy Cobalt we changed the transmission and now our car won’t start and the transmission won’t roll even when it feels like it shifts out of park

        • Look in your manual about immobilizer and it should tell you… my acura has a green key emblem that shows up flashing for an activated immobilizer. Your manual should have suggestions that might work, but mine says if green key still flashes contact dealership.

          I had to physically go to the dealership with my car registration and picture id to get the immobilizer code that allows you to by pass your immobilizer. It is unique to your vin# and doesn’t cost anything to get from the dealership. If you don’t have AAA it’s also cheaper to have someone drive you to the dealership as opposed to getting your car towed there.

    • Another tip: on the dash board you may see a symbol of Key outlined with vehicle. if that’s the case. be sure its your immobilizer.
      If you always throw your key or let your key falls or worse you give them to the kids to play around with or even pouring water on it. you will definitely have this issue one day.

    • Hi Sakhile I just joined the group and came past your post my 2004 1.6 golf is doing the same thing, I think it the mobiliser it tripped itself and the car doesn’t start only cranks up. Just replaced the battery and my mechanic had just cleaned the injectors, replaced the fuel pump the day before all this started

  3. My GMC Canyon will not even turn the engine over. It will crank remotely but when you put the key in it and turn it on it stops. The imobilizer light is on . How do I turn it off?

    • Do you have a 2nd key you could try (to rule out damage to the key transponder)? Most car manufacturers have a way to “reset” the immobilizer. You will need to contact a dealership or do some Googling online. Here are instructions I found for the Canyon’s cousin, the Chevy Colorado, if you want to try:

      1. Attempt to start the truck by turning the key to the Start/Run position. Try to crank the vehicle. 2. Observe that the vehicle fails to start and the security light is illuminated. 3. Release key to the ON/RUN position (not the ACC position or OFF) 4. Allow the vehicle to sit with key in the ON/RUN position for no less than 11 minutes. Security light will turn off after this. 5. When the light goes off, turn key to OFF position and allow the vehicle to remain in the OFF position for no less than 30 seconds. 6. Repeat #1-#5 for four cycles or until vehicle starts.

      It’s possible the immobilizer is simply bad and will need replacing.

    • The mobilize, must turn off soon as you put a key, if not key it lost coding or trandsponder is damage, then key programming is essential

  4. Damage to the transponder inside the key fob is possible. Also, make sure your steering wheel is simply not locked. While turning the key in the ignition, turn the steering wheel all the way to the left or right. If that doesn’t help, you’ll likely need to visit a local dealership to troubleshoot.

  5. I have a Peugeot 207 2007 and the engine cranks but doesn’t start its showing anti theft faulty my key does open and locks the doors also goes into economy mode after a while do you think it’s the transponder chip? Let me know thanks

    • Yes, the will cause a battery drain on most cars. Some newer cars will detect the drain and automatically shut things down. On pre electronic ignition vehicles (80’s and earlier), you can actually cause damage to internal parts (fuel pump, starter, etc.) by leaving it in the ON position too long.

      • I have honda vezel RS 2017 Japan domestic model, the key sign warning light is on while driving. The fob immobiliser works fine, open, lock and start etc all are ok.
        I went honda dealer, the electrician spent whole day checking all of wires etc. The OEM scanner also don’t show any faults. But the warning light is there.
        Since it is a Japanese model so all language is Japanese, which do not help.

  6. I have a Vauxhall tigra, over the last few days the car has been struggling to start or cutting out after starting, but then drives fine when it does start. Took to garage and codes read it is an incorrect key, could this be the reason for the car not starting/cutting out? Had the car a year and never had a problem with key before?

    • Have a mitsubishi Lancer has problem starting, have been told it is the key, it cranks but doesn’t start,.notice if the engine lights off it will start but if it flashes back on it will not start… also the fan runs loud as soon as key on 1st turn.
      Any suggestions
      Thanks in advanced

  7. When I open car door hazard lights flash 65 times sometimes anti theft system comed up on dash and ssys faulty dosent start sometimes any clues peugeot 607 2lt hdi

  8. There is this Toyota spider 2010 model that I’m currently working on that has engine immobizer fault.. the amplifier key ring is ok.. the immobizer transponder have been changed . Bt when programmed, the fault will go, but will still return after some time. The key light is also perfectly working.. the car always makes attempt to start bt drops.

  9. Hi. So, upon erasing 2 admin keys on my Ford, and then adding 2 new ones (I had lost one of the Admins and had to do the whole thing) now, both the keys work fine but every time I use the first key that was programmed it “cycles” the locks closing all then opening all doors once it reaches the ‘on’ position. It is not affecting performance whatsoever, as the doors do lock once I reach about 10 mph. Will I need to go back to the locksmith and re-do this whole process, or is there something I can do to stop the ‘cycling’ my key is doing every time?


    • You will likely need to take the key to the dealership to have it re-programmed. They should fix their error.

  10. once my 2017 hilux 3.0, alarm remote was torn up n I’m sending it to change a new cover for the remote. but I not able to unlock or lock my car after the changed of the cover. another fault is the immobiliser, it triggered the alarm when I try to push the immobiliser at its place. I think the locksmith has do something with it or accidentally swap it with other. how do I know if the immobiliser is belong to my car.

  11. My A4 B8 is not starting showing message on cluster ‘L3 2/2’ previously it was showing ‘SAFE’ but it was cranking, now it does not even crank.

  12. I have a 2007 Nissan Sentra. When I insert the key into the ignition it will not turn at all. The key fob still works to unlock and lock the doors. Could it still be the chip in the key even though it works on the doors?

  13. A personal experience. Maybe someone out there might have an interest. A have an old Opel Vectra B, gasoline. A couple months back I had problems with the key fob. I couldnt open the doors. A keymaker told me the electronics inside the fob died. Not the small chip. So he suggested I should replace it with new a one. I agreed. I had the security code from earlier when I replaced the ECU. He took some time to programm the new key. From that day on, if I was lucky enough, the car would start in the first attempt. If I would try to turn it off and immediately start it on, it wouldnt do that. Only after 3 to 4 attempts. Even if it would start, sometimes the engine would just die. Like if someone would cut off the gas pump. Today, after reading this site, decided on my one to do something foolish. I took the old electronics and put it back in. The problem was gone instantly. Now…I cant only remotely open the doors. Who cares!!!!

  14. Hi. The opening button on key fob for my Peugeot 107 broke so i bought a new one and put the old key chip and key part into new case. Although I can still use the lock buttons my car will not start…only turns over. Could removing the key from the chip have severed the ‘contact’ between them? Please can you help. Thanks

  15. My 2007 Ford Explorer will crank up an run fine but as soon as I cut it off it won’t start back until the engine is cool down.

  16. My son has a Nissan Juke. He has lost his key and has tried to code the new key to the vehicle. Follows all instructions and the hazards flash as expected to do so but the car won’t start. Any ideas on what this could be please . Many thanks

  17. hi i have a city golf 1300 cab 93 year 3 years ago i put in a radio and a immobilizer and an alarm put in and now all of a sudden i am driving and my city golf cuts off you have come to a stand still first put off the engine and then switch it back on and it starts again and off you go for a few mins and then it dose it again .i have replaced the spark cables fule pump return valve carb has been serviced fuel filter has been replaced again the brushes in the alternator as-well been replaced and yet it still does this to me please help its driving me mad

  18. I have a 2014 Honda Fit Hybrid. The key fob can open and close the doors but cannot start the car, not even the ignition light come on. No light at all on the dash board not even the key light. I need advise

  19. I have a question. I just had issues with my immobilizer not allowing me to start it. I got the brake code from Acura (2000 Integra) put it in and the car started (with the green key solid) drove it 40 miles to the dealership and made appointment for next day (pain in the arse because I basically had to tell them exactly what I wanted: Immobilizer Brake Code, and then no one but a mechanic that worked there for over 10 years could tell me how to use it). Anyhow, none of my 3 original keys would work before the brake code was entered, however now since using the brake code once, my car starts up normally… with no flashing/solid green keys… just like it did before it was halted by the immobilizer.

    Does anyone know why this is, or was it just a strange glitch in the immobilizer system? Thanks

  20. Hi my mobelizer is not working since when i remove the batter from the car when replacing it back then the problem started car is unlocked only problem is alarm siren and is not starting but key can turn the vehicle on pls assist

  21. I have a Toyota passo but the transpond (the key)isnt working since last week nd it’s been problematic for about 3months
    I’m asking for contacts details where I get the transpond I want to replace it

  22. i have a Mitsubishi RVR 2011 with remote start. i can remote stat the rvr but as soon as a touch the brake it stop as usual but now when i push to start , i have immobilizer system service required. did try with the key in the glove box slot, still stop when brake applied but still wont start and when i push to stop and leave they wrote in the dash don’t forget your key. car still at the dealer, they change first ecu computer, same problem, won’t start ,they just call to change another computer.

  23. Wow, I knew about engine immobilizers but had no idea they had such a massive impact on theft, dropped by 40% is huge. The only bad thing about the electronic ones is that if you lose the fob it can cost you a lot to get a new one programmed from the dealership but totally worth it if it can save your car from being stolen. Great post, thanks for sharing!

    John Crenshaw


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