Jeep Commander Won't Start, Immobilizer Issues Fix

As someone with moderate car repair experience, I dealt with a very similar issue on my 2009 Jeep Grand Cherokee Diesel. The symptoms matched exactly what you're describing, intermittent starting problems and sudden engine shutdowns, which turned out to be related to the car immobilizer system. The key signal was not being properly recognized by the vehicle security system. After several failed attempts to resolve it myself, I took it to a workshop specializing in key programming. They diagnosed a fault in the immobilizer communication and reprogrammed the key. The total cost was 45 Euro, which was reasonable considering the specialized equipment needed. The fix took about an hour and has worked perfectly since then. The key programming resolved both the starting issues and the error codes. To provide more specific advice for your case, could you share: Are you using the original key or a replacement? Does the security light stay on when trying to start? Which specific error codes are you getting? Have you had any recent electrical work done? These details would help determine if your issue is identical to what I encountered with my Cherokee.

Last service was at 117826 KM and my mechanic checked the car electronics thoroughly. I tried cleaning the key contacts and checking fuse connections, but the ignition control module still acts up. The security light does stay on longer than usual, about 3-4 seconds after inserting the key. Using the original key, no aftermarket parts involved. Getting error code P1684 which points to an immobilizer communication issue. The immobilizer bypass methods suggested online seem risky and could potentially damage the system further. Starting to think I need professional diagnostic equipment to properly address this car immobilizer problem.

Thanks for those details, the P1684 code on your Commander matches exactly what I saw on my Cherokee before getting it fixed. After trying the same basic troubleshooting steps you mentioned, I learned that DIY immobilizer bypass attempts often cause more problems with the anti-theft system. The extended security light duration you described, about 3-4 seconds, is a clear indicator that the immobilizer isnt properly reading the key signal. In my case, what looked like a simple key recognition issue actually stemmed from a failing antenna ring around the ignition cylinder. The specialized repair shop found that while my key was fine, the antenna wasnt consistently picking up the transponder signal. A new antenna ring plus reprogramming solved both the security light delay and the starting problems. Given your identical symptoms and error code, Id recommend skipping further DIY attempts. The risk of damaging the remote start and security components isnt worth it. Professional diagnostic equipment is really needed to properly reset and reprogram these systems, learned that the hard way after wasting time on temporary fixes. Would be helpful to know: Have you noticed any other electrical oddities lately? Does the problem occur more often after the engine is warm? Have you tried your spare key if you have one?

Appreciate the detailed response. After reading about the antenna ring issue you encountered, I checked my spare key and got the same problems, unusual starting failures and security light delays. My Commander also shows similar electrical quirks like occasional instrument cluster flickers, which probably points to the same antenna ring failure you mentioned. The starting problems definitely get worse after the engine warms up. Given the matching symptoms and that P1684 error code, I will stop messing with DIY fixes for the anti-theft system. Already called a shop that specializes in car electronics and immobilizer programming to book an appointment. Since the security light behavior matches what you experienced with your faulty antenna ring, I feel more confident about the diagnosis now. Hoping the repair costs stay reasonable like in your case. Will update once I get it fixed in case others run into similar immobilizer issues with their vehicles.