What could cause high oil pressure reading? on 1990 Chevrolet 2500 Pickup

My 2006 Chevy truck with a 6.0 has started showing 80 PSI on my gauge. What causes this? Is it the gauge or the pressure switch? Where is the switch located on this truck?

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1 answer
As a tech I would remove the sensor switch. Install a good guage and see what the actual pressure is. If the pressure is not the same as say 80psi I would put a new sensor in and see what it shows on your dash guage. If it still was showing high pressure then the dash cluster would have to be exchanged or repaired. Most oil pressure sensors are side of engine block near oil filter.