Question 1

My key fob shell is cracking and I think the emergency blade inside is uncut. Can you sort that out without reprogramming the whole key?

Accepted Answer

Yes, and this comes up more often than you'd think on XJs that have changed hands a few times. The smart fob carries a hidden emergency blade inside the housing, and on vehicles bought at auction or through secondary dealers, that blade sometimes never got cut. If your shell is cracked or the blade is missing or uncut, we can transfer your existing electronics into a new shell and cut the emergency blade to your vehicle. No reprogramming needed for a shell swap as long as the internal components are intact. We verify the blade fits your door lock cylinder before we leave. If the board inside is damaged rather than just the shell, that becomes a full replacement and programming job, which we also do on site.

Question 2

What exactly is a smart key and how does the 2015 XJ use it?

Accepted Answer

Your XJ uses a proximity-based smart key with a transponder chip inside the fob that communicates with the vehicle's immobilizer before the engine will start. The fob has five buttons and runs on a CR2032 battery. Beyond the remote functions, the fob also contains a physical emergency blade tucked inside the housing, which gives you a mechanical backup if the fob battery dies or the electronics stop responding.

The emergency blade matters more than people realize until the moment they need it. Knowing where the hidden keyhole is on your specific door handle before you're locked out is worth checking once.

Question 3

My 2015 XJ is showing a key-not-detected warning. Where do I start?

Accepted Answer

Start with the CR2032. A weak battery in this fob produces exactly that warning, and it can fool you because the fob may still unlock the car from close range while failing at the start button. Swap the battery first.

If a fresh CR2032 doesn't clear it, hold the fob directly against the start button. Most XJs have a backup transponder reader built into or near the button for exactly this situation. If the car starts that way, you've confirmed the fob is alive but the proximity system is struggling, which could be a fob antenna issue or a low battery that's still marginal even after a swap.

If the warning affects both fobs at the same time and neither one responds held against the start button, that points away from the fobs and toward a vehicle-side antenna or module problem. That's a diagnostic visit, not a battery swap. Call us and we'll figure out which side the fault is on before replacing anything.

Question 4

Can I add a second smart key to my XJ myself, or do I always need a technician?

Accepted Answer

You need a technician with the right diagnostic equipment. There is no ignition-turn sequence or button trick for adding a smart key on the XJ. The fob has to be registered to the vehicle's security module through the OBD port using professional software. That's true whether you're adding a spare or replacing a lost key. If you already bought a replacement fob online, bring it to us. We can program a compatible fob on site. What you want to avoid is someone using an underpowered generic tool that completes only part of the process, which leads to the crank-and-stall situation described above.

Question 5

I lost both keys to my 2015 XJ. Is all-keys-lost even possible on this car, and how long does it take?

Accepted Answer

It's possible and it's a job we handle. All-keys-lost on the XJ is more involved than a spare-key add because the security module has no existing registered key to reference during the process. The procedure requires reading data from the module, generating new key files, and writing them out correctly so the immobilizer accepts the new fobs as the only authorized keys.

Plan for it to take longer than a standard add-a-key appointment. There are timed sequences built into the process and the data read has to be clean before anything gets written. We come to you in Encinitas with everything needed to do it on site, so you're not towing the car anywhere.

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