Buick GL8 Security System Kills Engine Mid-Start

Had a similar issue with my 2010 Buick LaCrosse last summer. The security light kept flashing and the key signal was not being recognized properly by the immobilizer system. The car would crank but shut off immediately, exactly like your symptoms. Initial checks should focus on the key transponder and immobilizer bypass system. In my case, the problem was a failing key transponder chip, not the immobilizer itself. The repair required reprogramming of both the key and the car security system. This is unfortunately not a DIY fix as it needs specialized diagnostic equipment to sync the immobilizer with the key. While waiting for repairs, there is a temporary 30-minute reset procedure: Insert key, turn to ON position for 10 minutes until security light stops flashing, turn OFF, repeat 3 times. This sometimes allows a temporary start but is not a permanent solution. This turned out to be a serious electrical issue requiring professional intervention. Without proper programming, the immobilizer bypass cannot be completed, and the car will continue to shut off. The remote start system may also be affected if equipped. The root cause is usually either a damaged key transponder or corrupted security system programming, both requiring dealer-level diagnostic equipment to resolve properly.

Thanks for helping me with that immobilizer fault issue. The fix worked but now the remote start occasionally acts up too. The mechanic mentioned this might be connected to the original immobilizer problem we discussed. Curious, do you remember roughly what the key programming ended up costing you? And have you had any other electrical gremlins pop up since getting it fixed? Just want to know if I should expect more issues with the car immobilizer or ignition control system down the line.

After seeing the mechanic, my immobilizer problem was completely resolved. The key programming cost came to 45€ which was reasonable considering the specialized equipment needed for proper anti-theft system configuration. The remote start functionality should stabilize once the new programming fully integrates with the car immobilizer system. These components work together as part of the overall security setup. Since getting the key reprogrammed, I have not experienced any additional electrical issues or problems with the immobilizer fault codes returning. From what I learned, once the key programming is done correctly, these systems tend to remain stable. The initial problem often stems from corrupted programming rather than hardware failure. Just make sure to keep your spare key in good condition and avoid exposing the electronic components to extreme conditions that could damage the transponder chip. The peace of mind was worth the repair cost, knowing the car security system is now functioning as designed.

Thanks everyone for the helpful advice. Just wanted to close the loop on my situation. Finally took it to a mechanic yesterday who diagnosed and fixed the immobilizer bypass issue. The key programming cost me €65 and took about an hour. They explained my original key had a damaged transponder chip that was causing the anti-theft system to activate incorrectly. The car electronics are all working normally now, starts right up every time with no security light. Much better than the frustrating no-start condition I was dealing with before. Really glad I got it properly diagnosed instead of continuing to try various reset procedures that werent fixing the root cause. Only wish Id done this sooner instead of struggling with the temporary workarounds. Having a properly functioning car immobilizer gives me peace of mind that the security system is actually doing its job now.