I've done the searches, read the threads and no it is not my vehicle's immobiliser system playing up, so please don't go there. I've owned this Xc for the best part of ten years. It came with two ignition keys (with plips) and a valet key. They have always worked with the car, opened the central locking and started the engine. I have never changed the plip batteries until now, this week. Even so, suddenly one key is still working the CL but is rejected when it comes to starting the engine. So, 1. has anyone elese experienced this? 2. is there any remedy, bar going to the stealer with all keys and having them re-synced? I have Vida/DiCE can I sync the keys myself!