The yellow tyre pressure monitoring system warning lamp (pressure loss/malfunction) is lit.
The tyre pressure monitoring system has detected tyre pressure loss in at least one of the tyres.
The tyres may burst, especially as the load and vehicle speed increase.
The tyres may wear excessively and/or unevenly, which may greatly impair tyre traction.
‑ The driving characteristics, steering and braking may be greatly impaired.
You could then lose control of the vehicle.