2017 Ford Ranger 2.2 tdci limp mode on highway

Good day all

I recently bought a second hand 2017 Ford Ranger 2.2tdci pick up truck with 112,000 km on the clock.
Vehicle drives beautifully.
When driving on the highway however, after about 50 or 60 km's of continuous driving, the vehicle's transmission light comes on (orange gear cog with exclamation mark inside of it).
Vehicle then loses all power especially with uphills (limp mode activated).
When switching the car on and off, it goes away.
This happened twice in one day (driving to destination and back).

I informed the dealership who agreed to scan the Ford to see what error codes are picked up.
The only consistent error code that comes up is the PO672 glow plug #2.
The technician does not believe that this error code will cause the vehicle to go into limp mode.

My question is, will a PO672 error code cause the Ranger to go into limp mode?
Is a PO672 code actually a more serious issue than what I was led to believe?

I need this vehicle for a farm which is 100km's away. I cannot have a vehicle that does this.

Thanks in advance.

KM