16.2 bar = 1,620 kPa
Your pressure gauge may be broken....If it fluctuates, then you know its not your gauge, but if your gauge always reads 80, it may need to be replaced.
Reverse airflow feels a chamber inside the gauge and reads the pressure equal to the inside of the tyre its that simple. Same for air compressure, when the pressure is applied it seals the valve on the gauge end then back pressure fills the chamber inside the gauge when you release the gauge from the tyre valve the pressure has gone!!
It means the filter needs replacement
It is an electrical devise that "measures" the oil pressure and converts it into an electrical signal that a computer or the gauge cluster reads.
Low Coolant or faulty gauge
Yes. That is most likely a sensor malfunction and will do no harm. Zero pressure is when you worry.
Need to hook up a oil pressure gauge in the place were the oil sending unit is on the engine and see what the gauge reads, You should have no less then 20 LBS. at a idle. If it does not have oil pressure then pump is bad.
You might plan to refuel when your fuel gauge reads one-eighth of a tank of gasoline. Some people choose to refuel when the gauge reads one-quarter of a tank remaining.
It's low on freon.
Use a delta-p gauge
A pressure gauge measures pressure in a system relative to atmospheric pressure, displaying the reading in units such as psi or bar. A manometer measures pressure by balancing the weight of a liquid with the pressure being measured, often displaying pressure differentials in terms of inches or millimeters of the liquid column. In summary, a pressure gauge gives absolute pressure readings, while a manometer measures pressure differentials.