This procedure might get your 'wonky' oil pressure sender to read correctly
again. If this doesn't do the trick, you should first check the wiring
between the gauge and the sender. More likely, you probably need a new
sender, or possibly need to replace the gauge itself.
1) Car not running. Locate the oil pressure sender. On many of our cars it is located on the oil manifold at the block, which is where the oil feed line to the turbo is attached, below the thermostat housing.
2) Car not running. Use a wrench to loosen the oil pressure sender until it turns freely by hand. Unscrew it further until it comes off.
3) Car not running. By hand, screw the oil pressure sender back in only three or four threads. It should be loose enough to turn easily by hand.
4) Start the engine. With the car running, loosen the oil pressure sender until it begins to leak a bit. DO NOT completely remove it, as that would be very messy... Be careful to avoid the radiator fan, as the fan may come on at any time. Let the sender leak for 10 or 15 seconds; you don't want a stream of oil, just a few drops.
5) Engine running. Tighten the sender by hand until it no longer leaks.
6) Shut off the engine. Tighten the sender with a wrench. It doesn't need a lot of torque, but does need to be firmly seated.
You are now done. If all is well, the oil pressure gauge should now
work properly. Otherwise, you might have a loose connector at the sender,
or need to replace the sender or even the gauge.