what can be the cause for this alarm, if vehicle speed sensor is not installed in the vehicle.

Question

Vss: P0500 code is being displayed upon diagnostic. But the vehicle speed sensor is actually not installed in the car by default. The does not have ABS, and the speedometer is also mechanical.
Any possible reason why this code is being generated.

Also, after i have started getting check engine warning light due to this error, my engine stops if i drive the car above 140kph for around 15 minutes continuously.

Any correlation between the problem?