The Mk3 has an Oil Pressure guage and a Coolant Temperature guage.
Both do not give a direct reading of the values concerned.
Stop taking any notice of them, they are part of the incar entertainment system, the coolant temperature guage does not give warning of a cracked coolant tank until the cylinder head is warped.
Check the neck of the coolant expansion tank for any cracks and replace if that is the case.