Again, the pressure gauge only shows the difference between the pressure inside and outside the boiler. At sealevel 1.4 bar on the gauge means 2.4 bar in the boiler (using the standard difference of 1.0 bar). At an altitude of 2000 meters 1.4 bar on the gauge corresponds to 2.2 bar in the boiler. In other words the pressure in the room is only 0.8 bar at 2000 meters (again this is only approximate and depends on the weather etc). So at 2000 meters the temperature in the boiler is about 123 degC when the pressure gauge shows 1.4 bar compared to about 126 degC at sealevel.
In addition, the difference between high and low pressure due to the weather can be 0.1 bar which means that the temperature in the boiler can vary with about 1.5 degC due to the weather conditions.