Oil pressure gauge reads high all the time when engine on

1. Oil Pressure Gauge Not Working You will notice this happens when your oil pressure gauge is not reading, whether the engine is turned off, idle or running. Try to step on the gas to rev up the engine. If the oil pressure gauge still doesn't change its reading, your gauge is busted. It's best to replace it as soon as possible because you won't have any idea if your car is already overheating or not.
2. Oil Pressure Gauge Reading Too Low When your engine is idle, the oil pressure gauge will have a low reading. When the engine starts running or when you're already cruising or on the freeway, your gauge's reading should have increased. If it stays on a low reading, then you now your oil pressure gauge is broken.
3. Oil Pressure Gauge Reading Too High Another common oil pressure gauge problem is when your oil pressure gauge is reading too high when your engine is idle or when it's turned off. Rep

that is a sign of the wrong oil grade. that truck takes 5 w 20 oil

see this tips and fix it. God bless you
The oil pump supplies oil to lubricate your engine. If the oil pump is worn or is not turning, the engine will suffer a loss of oil pressure, which may result in engine damage or engine failure.
The first sign of trouble may be a low oil pressure warning light, a drop in the normal reading on you oil pressure gauge (if your car has one), or the appearance of ticking or clattering sounds from your engine.
As a rule, most engines only need about 10 PSI of oil pressure for every 1,000 RPM of engine speed. Oil pressure will read higher than normal when a cold engine is first started because the oil is thick. Oil pressure will gradually drop as the engine warms up and the oil thins out. So normal oil pressure on a warm engine cruising down the highway is typically 30 PSI up to 45 PSI.
SYMPTOMS OF OIL PUMP TROUBLE
The first thing you should do if any of these symptoms occur is to stop your car, turn off the engine, let it sit for a few minutes, then check the oil level on the dipstick. If the oil level is at or below the ADD line, add a quart of oil to bring the level back up to the full mark. Add as much oil as is needed to raise the level to the full mark. Then restart the engine. If the warning light remains on, or the oil pressure reading does not climb back up to its normal range, or the engine noise does not go away, you may have a bad oil pump.
The other possibilities include a bad oil pressure sending unit, or a problem with the oil pressure warning light circuit or oil pressure gauge.
OIL PRESSURE SENDING UNIT
If the engine is NOT making any unusual noises and seems to be running normally, and the oil level on the dipstick is FULL, but you are still getting a low oil pressure warning light or low gauge reading, the fault could be a bad oil pressure sending unit.
The oil pressure sending unit is mounted on the engine block. On some applications, there is a spring-loaded pressure-sensitive diaphragm with a switch inside the sending unit. This switch completes the circuit to the low oil pressure warning light if oil pressure drops below a certain threshold. The unit may stop working if the diaphragm inside fails, if the switch is stuck, if the small hole that allows oil to enter the sending unit becomes plugged, if there is a loose, corroded or broken wiring connector at the sending unit, or there is a fault in the wiring circuit between the sending unit and warming light.
On vehicles that have an oil pressure gauge (electronic, not mechanical), the oil pressure sending unit has a small rheostat inside that sends a variable voltage signal to the oil pressure gauge when the diaphragm moves. A worn spot on the rheostat or any of the other problems just described for the simple pressure-type oil pressure switches can cause a problem.
FORD'S FAKE OIL PRESSURE GAUGE
On many Ford vehicles that were built from 1980 through the 1990s, the oil pressure sending unit has two switches, a low pressure and a high pressure. These vehicles also have an oil pressure gauge, but the reading on the gauge is not a true indication of real oil pressure. As long as the pressure to the sending unit is between high and low, the gauge will read normal. If oil pressure drops and trips the low pressure switch, the dash gauge will now read low. Or, if oil pressure goes up and trips the high switch inside the sending unit, the dash gauge will read high. Consequently, don't rely on the oil pressure gauge for an accurate reading in these vehicles. It is only a gross indication if the oil pressure is low, normal or high.
OIL GAUGE PROBLEMS
If the engine is NOT making any unusual noises and seems to be running normally, the oil level on the dipstick is FULL, and you have replaced the oil pressure sending unit but are still getting a low oil pressure reading on the dash gauge, the fault could be in the wiring circuit between the sending unit and gauge, or the gauge itself might be bad.
Check the wiring connections on both ends as well as wiring continuity between the sending unit and gauge. If no wiring faults are found, hook up a pressure gauge directly to the oil pressure port on the engine and check oil pressure with the engine running. If the engine-mounted gauge shows normal oil pressure but the dash gauge is reading low, the problem is a bad dash gauge.
On the other hand, if the engine-mounted pressure gauge reads low and you have done all of the above, chances are the oil pump is worn, or it is not picking up enough oil because of a restriction or blockage in the pickup screen in the bottom of the crankcase.
OIL PUMP PICKUP PROBLEMS
The pickup tube has a screen on the end to prevent large chunks of anything bad that ends up in the crankcase from being sucked into the pump. But we are talking BIG chunks of debris, not normal wear particles or carbon or dust or other microscopic-sized abrasive particles that can cause pump wear over time.

Oil Pressure Test Check for proper oil pressure at the sending unit passage with an externally mounted mechanical oil pressure gauge. A tachometer may also be needed, as some specifications may require running the engine at a specific RPM.

1. While the engine is cold, locate and remove the oil pressure sending unit.
2. Following the manufacturer's instructions, connect a mechanical oil pressure gauge and, if necessary, a tachometer to the engine.
3. Start the engine and allow it to idle.
4. Note and record the oil pressure reading when the engine is cold. The engine may need to run at a specified RPM, if so check the vehicle's specification.
5. Run the engine until normal operating temperature is reached.
6. Check the oil pressure reading again with the engine hot and record the value. Turn off the engine.

Compare the hot oil pressure reading to the specification. If the reading is low, check the cold pressure reading against the specification. If the cold pressure is well above the specification, and the hot reading was lower than the specification, the engine may have the wrong viscosity oil. Change the oil, making sure to use the proper grade and quantity, and then repeat the test.
Low oil pressure readings could be attributed to internal component wear, pump related problems, a low oil level, or oil viscosity that is too low. High oil pressure readings could be caused by an overfilled crankcase, too high of an oil viscosity or a faulty pressure relief valve.

Look for the oil pressure sending unit on the block or the cylinder head on the V-6 or V-8 models. --- OIL PRESSURE TEST Check for proper oil pressure at the sending unit passage with an externally mounted mechanical oil pressure gauge (as opposed to relying on a factory installed dash-mounted gauge). A tachometer may also be needed, as some specifications may require running the engine at a specific rpm.

1. With the engine cold, locate and remove the oil pressure sending unit.
2. Following the manufacturer's instructions, connect a mechanical oil pressure gauge and, if necessary, a tachometer to the engine.
3. Start the engine and allow it to idle.
4. Check the oil pressure reading when cold and record the number. You may need to run the engine at a specified rpm, so check the specifications.
5. Run the engine until normal operating temperature is reached (upper radiator hose will feel warm).
6. Check the oil pressure reading again with the engine hot and record the number. Turn the engine OFF.
7. Compare your hot oil pressure reading to specification. If the reading is low, check the cold pressure reading against the chart. If the cold pressure is well above the specification, and the hot reading was lower than the specification, you may have the wrong viscosity oil in the engine. Change the oil, making sure to use the proper grade and quantity, then repeat the test. Low oil pressure readings could be attributed to internal component wear, pump related problems, a low oil level, or oil viscosity that is too low. High oil pressure readings could be caused by an overfilled crankcase, too high of an oil viscosity or a faulty pressure relief valve.
   

have u verified the oil pressure is low with a mechanical test gauge? many times a low oil pressure reading is no more than a defective oil pressure electric sending unit failure, so check the press with a gauge 1st.

the 1st thing that needs to be done is have a mechanical oil pressure test gauge hooked up to confirm the actual reading, the electronic gauge many times is incorrect.

the 1st thing u do is have the oil pressure tested with a test mechanical gauge by a shop, most times it is just the oil pressure sending unit is defective, but never assume that is the problem, low oil pressure will distroy a $5000.00 engine very quickly, u can just try a new sending unit, but highly recommend a pressure test with a mechanical gauge before you run the engine anymore.

faulty gage,replace

You need to have a mechanical test gauge hooked up to see if this is a false reading, this special gauge goes into the oil sender tap in the block and will let u know for sure if the pressure is to high cold, if it is the most common issues are wrong weight of oil, do u use oil heavier than 10W-30W? any other oil like 10W-40W will cause high oil pressure readings, the reason is the very tight rod and main bearing clearance's the engines now use, it is only about 1/2 the clearance of older engines, that is so the new fuel saving thin oils can be used.