BMW E38 oil pressure light on or flashing
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Why does the E38 oil pressure light come on or flash?
The cause can be a faulty or leaking oil pressure sensor, a worn oil pump or other pressure fluctuation. Replacing the sensor may fix the fault. Measure the pressure mechanically before replacing parts, so you do not replace parts unnecessarily.
What causes oil pressure fluctuation in the M73 engine when hot?
The bottom valve of the filter housing can cause the pressure to fluctuate. Test by pinching the return hose shut: if the warning light goes out, the fault is in the filter housing. New oil, a new filter and a new pressure switch do not help here.
Can loose oil pump bolts cause a pressure fault?
Yes. The M73's oil pump bolts can be loose, and securing the bolts with thread locker restores the pressure. It is worth checking the bolts whenever the oil pan is off.
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