Immobilizer malfunction - still runs

2008 Prerunner V6 6Speed Manual
130000 miles
Bluedriver pulled a code: B2799
Immobilizer malfunction
Truck turns on and drives. No issues.
Factory key.
Fob does not work. Tested new batteries in it. Still won't work. Lost other, Fob that did work.
Do I need to spend money on a new FOB?
My understanding is if the immobilizer doesn't work. Then the truck won't start.
I've had no issues starting my truck.

 

The immobilizer and fob are 2 separate things.
The fob plays no part in starting the truck.
The key is what let’s the truck start.

Here is simplified version of how the system works.
It’s not exact, but gives you an idea of how it works.

Ther key has a chip inside of it.
There is an Amplifier that strengthens the signal form the chip in the key, this signal is picked up by the Transponder ECU. The Transponder ECU tells the truck its
OK to start.