Lexus UX Key Battery Warning

I had something similar with my Renault. Keyless go stopped working sometimes. Have you tried the spare key to see if the problem persists?

Good call on the spare key! Haven't tried it yet. Wouldn't a dead battery in both keys be a coincidence? I'm tempted to open the key fob. What do you think?

It does seem like a coincidence, but try the spare first. If that doesn't solve it, a workshop visit might be worth it. With my Renault, it was a faulty receiver in the car, not the key itself. But the key battery was also empty.

You were right about the key battery. Replaced it, cost me 37€, and everything's back to normal. Keyless entry restored, error message gone. Simplest solutions are the best. Thanks for the nudge!