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I agree that a simple gauge did the job and I prefer them .. I have a mechanical gauge on my 250SL and it is great..NO electronics or sensors... but , along came 1996 and OBD11 code monitoring mandates .. and 4 of those codes monitor oil pressure system, gauge, and sensor circuit. So , the
existing sensor circuitry got modified to handle these new tech electronics.
OBD11 Codes Po520, 0521, 0522, o523 are all oil pressure/sensor system diagnostic feeback to ECU system monitoring, looking for faults.
If one scans the system, these faults monitor sw circuit, system voltages ,both high/low, and sensor/gauge range through the processor and tat will tell you if the sensor circuit is in range. [ but , the comparison test with a mechanical gauge is best]

It ain't a Benz thing , even Toyota has it...