Checking sensors and oil pressure (VW Transporter T4)

Checking oil pressure sensors 0.3 bar

There are 2 oil pressure sensors installed, which are triggered at different oil pressures. The 0.3 bar oil pressure sensor has brown insulation; the 1.8 bar oil pressure sensor has white insulation. Instead of the 1.8 bar oil pressure sensor, the diesel engine has a 0.9 bar sensor with gray insulation.

4-cylinder engine

The 0.3 bar oil pressure sensor is located on the end face of the cylinder head on the left in the engine compartment. The 1.8/0.9 bar oil pressure sensors are screwed on top of the oil filter bracket.

5-cylinder engine

Both oil pressure sensors are located on the left side of the cylinder block in front of the oil level indicator guide hole.

1. Check the oil level.

2. Check the wiring of both oil pressure sensors according to the wiring diagram.

3. Remove the oil pressure sensor 0.3 bar (brown insulation).

4. Instead of the oil pressure sensor, screw in a suitable pressure gauge.

5. If a VW gauge is to be used, screw the oil pressure sensor onto the test gauge.

Attention! The described check can only be performed if it is possible to screw the sensor into the pressure gauge. Otherwise, only 1.8/0.9 bar sensors can be checked.

6. Connect the test device to ground (-).

7. Connect a voltage measuring device using an additional wire (multimeter or diode indicator) to the oil pressure sensor 0.3 (A) and the positive terminal of the battery.

8. The indicator lamp or LED should light up.

9. Start the engine and gradually increase the speed.

10. As soon as the pressure gauge shows 0.15–0.45 bar, but not more, the control lamp goes out. Otherwise, replace the 0.3 bar oil pressure sensor.

Attention! If necessary, check the moment of operation of the oil pressure sensor when the engine is rotated by the starter.

Oil pressure sensors 1.8/0.9 bar

11. Disconnect the wiring from the 1.8/0.9 bar sensor (white/grey insulation).

12. Using an additional wire, connect a voltage measuring device (multimeter or diode indicator) to the oil pressure sensor 1.8/0.9 bar and the positive terminal of the battery.

13. The control lamp should not light.

Oil pressure sensor 1.8 bar

14. Increase the revs until the pressure gauge shows 1.6 to 1.8 bar. The control lamp should now light, otherwise replace the oil pressure sensor.

Oil pressure sensor 0.9 bar

15. Increase the revs until the pressure gauge shows between 0.75 and 1.05 bar. The control lamp should now light, otherwise replace the oil pressure sensor.

Checking oil pressure

1. Increase the speed to 2000 rpm. At an oil temperature of 80°C, the oil pressure at these speeds should be at least 2.0 bar.

2. Lower oil pressure indicates wear of the crankshaft main bearings.

3. Increase the speed even higher. The oil pressure should not exceed the maximum permissible value. Otherwise, replace the oil pump cover with the overpressure valve.

4. Install the oil pressure sensor with a new O-ring and tighten to 25 Nm.