Jaguar XK Immobilizer Fault, Secret Fix Revealed

Having dealt with a similar ignition control issue on my 2004 Jaguar XJ8, I can share my experience as someone with moderate experience working on these models. The symptoms you describe match exactly what I encountered, engine cutting out immediately and security light illumination. The immobilizer system was indeed the culprit. In my case, the key transponder wasnt being properly recognized by the car immobilizer module. The fix was relatively straightforward, reprogramming of the key to properly communicate with the immobilizer system. Total cost was 45€ at an independent specialist workshop. They used specialized diagnostic equipment to reset and reprogram the system. Before you proceed with repairs, could you confirm: Does the security light flash or stay solid? Have you tried using a spare key? Are there any other electrical issues present? Which fault code is stored? These details would help determine if youre facing the same issue or if theres potentially something else causing the problem. Sometimes these symptoms can also indicate a failing key transponder or corrupted immobilizer data in the ECU.

Just had my 96968 km service last month. I got my issue fixed yesterday. It turned out the key signal was weak due to a damaged transponder chip in the key fob. The immobilizer fault triggered when the security light started flashing rapidly. The shop did a full key programming session and replaced the transponder. No immobilizer bypass was needed. Total repair cost was 290€ including parts and labor. For others having similar issues, get the fault codes read first. A proper diagnostic scan will show if its really an immobilizer system problem or something else causing the no-start condition.

Thanks for the update on your XK repair. This matches what I experienced on my XJ8, these Jaguars are known to have transponder chip issues after several years of use that trigger immobilizer faults. The repair cost seems reasonable given the parts and programming involved. My key reprogramming was cheaper since I only needed a reset without replacing the actual transponder chip. These security light issues can be tricky to diagnose without proper scanning equipment. Good advice about getting proper fault code readings first. Many shops might jump straight to an immobilizer bypass when a simple key signal fix could solve the problem. The car immobilizer systems on these models are actually quite reliable when the transponder communication is working correctly. Also worth noting your preventive service likely helped identify this issue before it left you stranded somewhere. Regular maintenance really helps catch these problems early.

Thanks for the helpful replies on my XK issue. After getting the transponder chip replaced and full key programming done, the car is running perfectly with no more immobilizer faults or security light problems. For anyone else facing similar symptoms, the rapid flashing security light was the key indicator pointing to the immobilizer system issue. The weak key signal from the damaged transponder was preventing proper communication with the car electronics. 290€ was money well spent considering the specialized diagnostic equipment and programming needed. Much better than trying cheaper fixes that might not have solved the actual problem. Having the fault codes read first definitely helped pinpoint the issue and avoid unnecessary repairs. Really appreciate all the input from others who dealt with similar ignition control problems on their Jaguars. Having this knowledge beforehand made it easier to discuss the repair options with my shop.