Oil pressure switch

The oil pressure switch is bolted into the engine block beside the oil filter.

If the oil pressure falls to a level that is too low, the oil pressure indicator light lights up in the instrument panel.

Functional description

The oil pressure indicator light lights up if the oil pressure does not exceed a value defined by a spring. This value is approx. 0.2 to 0.5 bar. If the engine is started, the oil pressure opens the earth contact and the oil pressure indicator light goes out. The oil pressure switch is connected to the engine control system across a signal cable. The data interchange is digital.
Item Explanation Item Explanation
1 Oil pressure switch 2 1-pin plug connection

Structure and inner electrical connection

When the oil pressure switch is not activated, 12 Volts is applied to this signal line to the engine control system. When the switch is activated, 0 Volts is applied.

Item Explanation Item Explanation
1 Oil pressure switch

Pin assignments

Pin Explanation
SIG Signal, oil pressure switch

Nominal values

Observe the following target values for the oil pressure switch:
Variable Value
Voltage range 9 to 16 Volts
Minimum switching point 0.2 bar
Maximum switching point 0.5 bar
Operating point 6 bar
Temperature range -40 °C to 140 °C

Diagnosis instructions

Failure of the component

If the oil pressure switch fails, the following behaviour is to be expected:

Petrol engines

  • Check Control message without fault code entry with running engine
  • fault code entry in the engine control unit without Check Control message after stopping the engine, if engine oil temperature is above 60 °C

Diesel engines

  • No Check Control message, no fault code entry

General notes

Diagnosis of the oil pressure switch runs within 8 seconds after stopping the engine.

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