Fortuner Key Battery Low Warning

I had something similar with my Fortuner, although it's a newer model. Keyless entry went totally bonkers. Have you tried the spare key? Just curious if it's the car or the key itself. What error code are you getting?

Haven't tried the spare yet. Will give that a shot. Where'd you end up finding the fault? And how much did they charge to fix?

Spare key did the same on mine so it was definitely both keys. Honestly, I didn't even bother troubleshooting much. Just took it straight to the dealer, as I didn't want to risk messing anything up with the immobilizer. Best to get it checked at a workshop.

The spare key had the same issue, so I just swapped the batteries in both keys. That fixed it - cost me 37€. All good now.