5 Symptoms of Engine Immobilizer Problems

Last Updated on July 2, 2020

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.

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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.

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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. 

#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.

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.


130 thoughts on “5 Symptoms of Engine Immobilizer Problems”

  1. I have a 1992 Mercedes Benz 300se almost mint condition and I cant get it to start or crank The alarm on the outsidee of the dooors blinks red I have broke in windows what do i need to do to reset my alarm system

    • Hi David, check your owner’s manual for more information about your vehicle’s alarm system. You might be able to reset it with a button press from the key fob. If you follow the instructions and your car still won’t start, have the battery tested and check fuses next.

  2. 1. Engine Immobilizer System – indicator “on” light flashes could lower the battery?& could not start the engine after how many days without moving (start) the car?
    2. Or Engine Immobilizer System has recycling back to battery – without battery usage?

    • If your car isn’t starting after several days there could be a parasitic drain on the battery. The anti-theft system will have a draw but usually it takes weeks to deplete a healthy battery.

      How old is your battery? It might be good to have it tested or replaced. If the battery is new and tests good, try performing a parasitic drain test. Check out EricTheCarGuy for a great how to video on this test.

      • Due to Covic 19 various Senior(I) need to stay home
        My Toyota Corolla 2013 – light flashing when engine is off meaning the system is On.
        I start “idling” every 3 weeks – working fine. Just to confirm the Engine Immobilizer System won’t consume the battery power then engine won’t start.
        My toyota Corolla 2013 just has only 30,000 km usage (extreme low milage).
        Hoping you can advise me.

        • Yeah, that is pretty low mileage. I wouldn’t worry about the immobilizer consuming power. I’ve been running my vehicles once every week or two just up to operating temperature to keep the battery charged. You can also stick the battery on a battery tender if you’re concerned.

    • Now, you know my situation.
      Due to my vehicle is lower gasoline now. Could I wait 4 weeks or more weeks not to start (idling) the car in order to have no problems of : Starting the engine after the crisis & Engine Immobilizer System is “ON”.
      Hoping you understand my question. 🙂
      Thanks again.

      p.s. Your company is the best even Toyota not to reply my concerns!

      • It’s probably fine, but I don’t know the future. Worst case you just jump start it. If it were me, I would still start it every couple weeks and just let it run for a few minutes. It’s not going to use that much fuel, and starting the vehicle regularly will keep the engine lubricated.

  3. I have a chevy spark that cranks but no start..injectors are not supplying fuel. electrician diagnose said no pulse from Ecu took Ecu to get check no error code came up. They said its working fine, we checked continueity on wires and everything is fine somone told me it might be the ke since the car hasnt started for some months, any ideas?

  4. I have a 2016 chevy sonic and the immobilizer light came on and car wont start but my key fob locks and unlocks the doors is this going to cost me alot money if mu warrenty doesnt cover it

    • It may, depending on the root cause. Before you take it to a shop, check the owner’s manual for troubleshooting advice. It may end up being a simple fix.

  5. I have a Cheryl J11, 2011 which are not longer available here in Australia. No parts or servicers here anymore. My battery is draining overnight. The battery has been replaced and upon further investigation have found the fuse that controls the immobilizer unit is the problem. I now have to pull the fuse when not is use for more than an hour or two. I may be able to get a second hand part but how do I get the code for my car now and for the second hand part. No dealerships in Australia for several years now. Or is there another way to fix the problem. Everything else works fine keys, remote ECT. Thanks

  6. I have a 2008 infiniti g35x and the key lose program and I got a locksmith to reprogram and it not accepting the key and I had done it before and it work but something else is wrong what could cause that

  7. Please help me with my Hyundai Tucson 2007. For about 3 years now, the ‘immobilizer’ issue is on and off. Sometimes, I could start the engine without any difficulty. At times, the ‘ignition key’ light keeps on blinking and I cannot start. I had to wait for a while and after several attempts, when I reinsert the key, the light stops blinking and the car would start.
    Can I just by-pass the immobilizer? How can I do it? I don’t need it. Nobody will steal my car. Beside being old, there are no car theft here in Dubai.
    Thanks 🙂

    • There may be a factory way to disable the immobilizer. See if you can get your hands on a factory service manual, as it will include a way to do this if it is possible to do without physically disconnecting the immobilizer.

  8. I have a 2011 BMW 328i with a no crank no start issue. It was diagnosed and was told it needed new CAS unit and new ignition switch. Replaced both, had it aligned with the DME and it still is no crank no start. Any ideas what the issue is?

    • The immobilizer is a good next guess. If the vehicle doesn’t even crank, I wouldn’t suspect the CAS is the cause. Usually a bad crank or cam angle sensor will let it crank because the starter has power, it just won’t start because the ECU can’t tell when it’s supposed to fire the spark plugs.

  9. Thank you for this fantastic article. I am in Europe and have a 96 VW Golf Cabrio, that I just bought in March of this year. When it was new, the original owner had the dealership install a Texalarm immobilizer. At that time, there was just a fob with a button that talks to the immobilizer, it’s not on the key fob (just a key). Yesterday I pulled into my garage and the car shut down abruptly and wouldn’t restart. The immobilizer light was flashing, meaning it was ‘on’. The car does not have remote unlock, but I tried everything, to no avail. Today I tried the second fob and it works fine. Since Texalarm no longer exists, I can’t get replacement fobs. But I’m now nervous because what if the 2nd one fails, I won’t be able to use the car at all. I will replace the batteries. However I think I will contact an auto electrician to have him either disable, remove or replace this immobilizer with a newer one. It’s more of a hassle than a benefit, if you ask me.

    • Good thinking. I’m glad you were able to get it working with the second key. If you check the owner’s manual, there may be a way to bypass the immobilizer yourself if it was a factory option (I’ve never heard of Texalarm so I’m not sure).

      You could also try replacing the battery on the first key and see if you can start the car with that key again. If so, I might just keep a couple spare batteries on hand and call it a day.

  10. I have a 2001 mazda tribute and it just died one day and towed it home. Well letting is sit there the battery had died and so I tried to have someone jump me and as soon as I turned the key over the immobilizer system light started flashing really fast so I ended up putting another battery in the car and now when you put the key in it comes on maybe once and dont come on again at all. But the car with still crank trying to start but nothing. I change the fuel filter and you couldnt get any air through it but still I got nothing. Any thoughts?

    • If your car died while driving, I would address that issue first; that was probably not caused by the immobilizer.

      Start with the basics – make sure the engine has air, fuel, spark, and compression. After you’re sure those are good, then start troubleshooting the immobilizer.

  11. Sometimes my car get started and sometimes not when if there is rainfall. Engine immobilizer red dot blink continuously when it is rainfall but lock unlock of door functions well by remote key. What will be the problem. Renault Duster, model of 2012

    • Sounds like what would happen if water got underneath your distributor cap, but I don’t think that car has a distributor. Check to make sure there aren’t any leaks in the engine bay that could flood the ignition system with water.

  12. I bought an old Peugeot 2003 206cc. Electrics kept cutting out while driving, changes the battery, sealed the rear lights as one had water in it, sanded the metal contacts I could get to, dropped IPA into the connectors I could find…..still had the same problem, though backlights for the A/C came back on and everything started running smother. Finally replaced the battery in the keyfob with a high quality one…..no problems since. The car was cleaned within an inch of it’s life by the dealer I bought it off….windows needed silicone greasing to stop the squeak, they had clearly washed the engine and painted a couple of bits of rust, speakers were blown and the radio was knackered. As a total novice going in, I can now do a lot with the car….so failing to do the 1st simple thing led to a greater knowledge. I was surprised the low battery in the keyfob caused a fault while the engine was running, but it obviously did. I was about to work on the ECU (It seems simple enough to refurbish) but I couldn’t see it being the ECU as it’s 17 years old and had obviously not had that fault all the time. Sometimes a £2 battery really is the solution, not tearing the car to pieces.

  13. My ongoing effort to save money by first isolating immobilizer problem has been educational if nothing else:
    I have an intermittent no crank/no start problem on my 2012 Chrysler 200 Limited and because I could always alternately remote start my car but after inserting the key into the ignition killed it, I concluded the immobilizer MAY be defective. My car required 9 hours and a lotttttt of studying videos and posts to disassemble nearly the ENTIRE dashboard to access the ignition switch and immobilizer riding on it. Then the process of trying to locate a locksmith (often suggested) to do the replacement job with a factory new immobilizer was a lesson in futility. Many say they can, but can only read the current immobilizer pin, if you get if for them from the dealer. This allows them to reprogram keys and make them think they can replace an immobilizer without the $3,000 piece of equipment it takes to extract the pin from a new immobilizer, much less update the ECU as well. And just where does that leave the next owner who calls the dealer for the pin? Do they get the old retired one? I placed an ad on Craigslist for a week as a gig for a qualified locksmith to do the job for $200.00 and did NOT get a single reply. However, it took me an inordinate amount of time, stress, inconvenience, trial and error, study and mechanical chores to even know the right questions to ask without a fix yet in sight.
    I am even wary of the dealer now who confesses that they can’t specifically test an immobilizer and will still want $88.00 for a diagnostic before replacing the immobilizer with a matching factory new that I bought online. The dealer still quotes $350+ minimum EVEN WITHOUT DASH DISASSEMBLY AND RE-ASSEMBLY! And wait, they want $50 more to use my two new key fob/blanks also. And the final kick in the crotch is that there is still no guarantee of a fix! I have posted this story, including a long list of steps for dashboard disassembly in the 2012 Chrysler forum on reddit. Best of luck to you DIYers when it comes to addressing immobilizer problems when even the pros weep in ignorance.

  14. I want my next car not to have an immobilizer. Can I find a new car without immobilizer? Car manufacturers, let the police handle the car thieves, don’t make the consumers pay for a feature they don’t like.

  15. I have a Golf 5 2008 fsi ,if cranks but does not start, and if I turn on the key I can see petrol pump works, then if I bypass petrol it starts.
    so what is the problem with this?

    • I’m not sure what you mean by “bypass petrol”, but try to narrow down if it’s an electrical issue like a bad immobilizer or a mechanical issue with the fuel pump or a fuel restriction.

      Are you able to get it started by giving it a little gas while you crank it?

  16. Hi I Kenneth my car was not starting some people were assuming that it might be a starter couple days l started to kick start my car but it wasn’t a good thing to do as l was about to take a starter out the following day same day that afternoon my car started but what l have noticed when l lock my car one side front and rear indicators are not coming on but when l m using hazards are working fine what could be problem

    • You may have an electrical issue that is both preventing the car from starting and interrupting the signal to the indicators. You’ll have to do some electrical diagnostics to narrow down the problem, because on the surface those two issues don’t seem to be related at all.

  17. Hi I have a Chervy spark 2016 model with after market immobilizer. everything was fine until covid in a result of i wasn’t driving a lot. My battery started to be drained and I thought its need a new battery … however the new battey get drained after two days if on driven. took the car for diagnosis they said there are no leackages on the battery they said it could be the tracker unit that is draining the battery. I took off the tracker a month ago but the problem is still there. I don’t know what to do now or should I disconnect this immobilizer. My car is on 46 000Km

    • Aftermarket stuff can be hard to troubleshoot, but that could definitely be the root cause of the problem if it was installed incorrectly. It sounds like an added system may be causing a parasitic draw when the vehicle is off. You could try removing the aftermarket immobilizer and see if the issue persists.

      Other possible solutions are disconnecting the battery (the ground terminal), or using a battery tender if you aren’t going to drive for extended periods of time.

  18. Hi

    I have a Hyundai Elantra J2 1.8 1997 which died on the road , we have done the entire engine and replaced the crankshaft sensor, the crankshaft had locked so we skimmed it now it turns but wont start..we done diagnosis and they said it’s the immobilizer as everything else it fine and the computer box shows no other errors now i have the immobilizer chip but it wont start still, what can i do to get it moving?

  19. HI Sean,

    I have an after market immobilizer and alarm on my 2003 Jeep Liberty. The keyless entry won’t unlock my doors nor will the original keyless entry (which I could use before when the after market was acting up or battery was dead). I was able to open my doors with the ignition key but the jeep still won’t start and no lights when I turn the key. I also noticed the blue immobilizer light wasn’t flashing for the first time either. Pretty sure it’s the immobilizer as it acted up before. I Any ideas how to start my Jeep? Your advice and info is greatly appreciated. Thank you!

    • What aftermarket system is it? Do they have a troubleshooting section in their user manual?

      I think the best thing to do would be to remove the aftermarket system and see if you can start the vehicle normally with the stock setup. If you must have the aftermarket system, you can try adding it back but pay close attention to the installation instructions.

  20. 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!

    • 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.

  21. 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

  22. 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!!!

  23. 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?

    • 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.

  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. 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?

  26. 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.

    • 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?

  27. 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!

    • 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?


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