Engine oil pressure/temperature sensor

A new combined engine oil pressure/temperature sensor is used. The pressure sensor signal is required for program map control of the oil pump and the temperature signal for engine heat management. The sensor is subjected in the main oil gallery to the prevailing oil pressure there and the engine oil temperature. This ensures that what is measured is now the actual engine oil temperature in the engine and no longer the engine oil temperature in the oil sump.

Functional description

The engine oil pressure/temperature sensor measures the absolute pressure of the engine oil and its temperature. The measured values are output as a pulse-width-modulated signal.

The measuring procedure is based on a micromechanical piezoresistive pressure sensor (silicon) which supplies an output signal proportional to the pressure. Temperature measurement is performed by way of a diode.

The sensor measuring range is 0.5 bar to 10.5 bar at permissible temperatures between -40 °C and 160 °C. The sensor is operated with a voltage of 5 V.

Index Explanation Index Explanation
1 Engine oil pressure/temperature sensor 2 three‐pin plug connection

Structure and inner electrical connection

The engine oil pressure/temperature sensor is connected by a 3-pin plug connection.

The engine oil pressure/temperature sensor receives its earth/ground and a supply voltage of 5 V from the engine control unit.

The pulse-width-modulated signal is split into 3 fixed cycles. The first cycle is for synchronisation and diagnostic purposes. The second and third cycles transmit the temperature and the pressure respectively.

Index Explanation Index Explanation
1 Oil pressure sensor 2 Oil temperature sensor
3 Evaluation electronics

Pin assignments

Pin Explanation
5 V 5 Volts, supply voltage
PWM Pulse-width-modulated signal, engine oil pressure/temperature sensor
Terminal 31E Terminal 31, electronics earth (ground) both sensors

Nominal values

Observe the following setpoint values for the engine oil pressure/temperature sensor:
Size Value
Supply voltage 5 V
Pressure measuring range 0.5 to 10 bar
Maximum power consumption 15 mA
Temperature range -40 °C to 160 °C

Diagnosis instructions

General notes

The sensor has self-diagnostic capability, enabling the temperature signal and the pressure sensor signal to be diagnosed separately. The diagnosis result is contained in the pulse-width-modulated signal and evaluated by the engine management system.

Failure of the component

If the engine oil pressure/temperature sensor fails, the following behaviour is to be expected:

  • Fault entry in the engine control unit
  • Emergency operation with substitute value

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