Will a flat keyfob battery prevent a car from starting?

[Diddums]

I feel like I should know this, but I'm doubting myself so here we are.

Sister in law's i10 occasionally fails to start. She's in Saffrica so hopping over to help out is a bit of a drive so I'm helping remotely (see what I did there?!).

She panics when it happens and she's a bit nuts so the question of "explain exactly what happens when you turn the key" is met with "dunno lol".

Anyway, she also mentions that the car doesn't always unlock when she presses the fob (which is 5 years old and still on the original battery) so the battery is obviously dying.

I'm assuming that the car has an immobilizer, the signal for which is transponded from the key. But will a dead battery prevent the signal getting to the car, leaving her stranded? For clarity she says if she leaves the car for 10 minutes it starts up just fine, which again supports my theory that the immobilizer locks out and needs a few minutes to reset before reading the key again.

Does this theory make sense? I'd have thought that the key has a passive chip but everything points towards the dead battery, so I need to rule that out.

 

[Diddums]

Thanks for the replies folks. It's not keyless, but I'm still quite suspicious of a dead battery. I've told her to use the spare key for a few weeks and see how it goes, I still reckon it's the dead battery in the key. As illogical as it might sound, my spidey senses are pointing in that direction. I'll report back in a week or two with the outcome

Thanks again, you absolute beauties <3