2021 Cadillac XT5
Key Replacement - Save vs Dealer in San Diego

2021 Cadillac XT5 Smart Key Replacement - Fast, Affordable & Professional

Out in Berry Park, Imperial Beach, a guy called me about a 2021 Cadillac XT5 that would crank, fire for a second, and then die. Every time. He had already paid another locksmith to cut and program a new smart key, and the locksmith had told him the body control module was faulty and walked away from the job.

I asked him one question before I drove out: did the other locksmith mention a security relearn timer? Silence. That told me what I needed to know.

On the XT5, the immobilizer enrollment is not a one-step write. The security system runs a timed learn sequence, and if power drops, the process stalls, or steps get skipped, the key data writes into a temporary state instead of committing permanently. The engine cranks because the mechanical start works, but the security system kills fuel almost immediately after. From the outside it looks exactly like a BCM fault. It is not.

I connected my diagnostic equipment through the OBD port, cleared the incomplete key data left behind by the previous attempt, and ran a clean enrollment from scratch with the full timed cycle. Watched the confirmation that the key was permanently registered before I touched anything else. Then I tested the start three times back to back, clean ignition, no cutoff, no warning on the dash.

The body control module was fine the whole time. The prior job was just left unfinished.

He had already paid once for work that did not get done. I could not fix that part. But I made sure he drove home that evening.

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