Oil pressure light comes on when engine warms up.replaced oil pressure switch .still the same . its an audi a3 2002

Does the oil light come on with the oil pressure sensor wires disconnected?
Is there oil pressure in the engine when it is running?

This could be a low oil pressure problem or a failing oil pressure sending unit (sensor). It could even be diluted engine oil. If it has been a while since the engine oil was changed, then change the oil and filter. If you still have the problem, then perform an oil pressure test and measure the actual oil pressure. It should not drop lower than 7 PSI at idle with a warm engine. If it does, then there is an internal problem with the engine like failing oil pump or worn bearings. If the oil pressure tests ok, then have the oil pressure sending unit replaced.

How is the sensor connected to the engine? I had a 2000 model Pajero which did the same thing. It had to do with the way the sensor was connected to the engine, the hollow bolt they used was aftermarket and didn't let enough oil through to the sensor. So the oil has to warm up first before it can get through to the sensor.

2010 audi oil light flashes intermittently

If by pulsing you mean that the idle is fluctuating up and down, this is caused by oil/sludge build up in the throttle valve. To rectify this remove the intake pipe at the throttle valve. Use engine cleaner/degreaser on a rag to clean out throttle valve around throttle butterfly. Open butterfly manually to assist access. The oil pressure light coming on is usually caused by the oil pump pick up becoming blocked by carbon and sludge in the oil sump. If you have a suitable oil pressure gauge, check the oil pressure at the oil switch. Oil pressure should be 3.5- 4 bar at 2000 rpm at operating temperature. If pressure ok, Pressure switch may be faulty. If pressure low you will have to remove oil sump and clean out or replace oil pump pick up. If not done, may result in major engine damage. Sludge and carbon build up caused by oil not being changed often enough. Best to use a synthetic oil.

Well, either you have a pressure issue or a transducer issue.

Pull the pressure switch and measure the oil pressure with a "known good" pressure gauge. If pressure is within specs, replace the pressure transducer (switch).

you have a low oil pressure prbolem. may need an oil pump.

There are potentially two different problems here.
1. A fault with the actual oil pressure.
2. An electrical fault with the switching circuit.

If you are confident the problem is not with the oil pressure, disconnect the wiring from the switch for a period of time. If the light still comes on periodically the fault must be with the wiring circuit shorting to earth. There will be no fire hazard to this approach as the voltage will drop over dash lamp.

However if the problem is with the oil supply system, the danger with this approach is you are potentially unaware of a serious problem

Such as the oil filter collapsed or the oil pressure release spring could be jammed open/closed which would cause the engine to not have the correct operating pressure.

THOSE NUMBERS ARE VERY GOOD, THE PROBLEM MOST LIKELY IS A DEFECTIVE OIL PRESSURE SENDING UNIT, HAVE REPLACED 100'S OVER THE YEARS FOR THIS SAME ISSUE, GREAT THAT U CHECKED THE PRESSURE THOUGH, IF THE LIGHT WAS INDICATING ACTUAL LOW PRESS U COULD HAVE WASTED THE BEARINGS IN THE ENGINE.

i think from memory that the oil pressure switch is at the back of the cylinder head, if its not there it will be located just above the oil filter, these switches are very cheep to buy and can be bought from any good motor factors. You are right to suspect the switch, its the first thing to eliminate before bogging your self down with more complicated and expensive problems.