Engine Oil Pressure: Testing and Inspection

Oil pressure and oil pressure switch, checking





Special tools and equipment
^ VAG1342 Oil pressure tester
^ VAG1527B LED test light
^ VAG1594A Adapter set

Function of the dynamic oil pressure warning indicator
^ When not under pressure, the oil pressure switch is open and will close when the operating pressure is attained.
^ The oil pressure warning will be activated approximately 10 seconds after switching the ignition on.
^ Switch-in delay of oil pressure warning: approximately 3 seconds.
^ Switch-off delay of oil pressure warning: approximately 5 seconds.

Note: Functional check and servicing the optical and acoustic oil pressure warning:

Refer to Electrical Wiring Diagrams, Troubleshooting & Component Locations

Checking warning lamp
After switching on the ignition without engine started, the oil pressure warning lamp in instrument cluster must light for approximately 3 seconds and then go out. The test will be terminated if the engine is running.

Criteria for warning
Switching on the optical oil pressure warning (the oil pressure warning lamp flashes) and the buzzer sounding three times for the acoustical warning will occur under one of the following conditions:
^ "Ignition on," engine stationary, oil pressure switch closed
^ Engine speed above 1500 RPM, oil pressure switch open

Note:
^ If the oil pressure switch is closed, the warning lamp will remain switched on if the engine speed is above 5000 RPM. The warning lamp will be switched off again if the engine speed is below 5000 RPM.
^ If the oil pressure switch is open for 0.3 - 3.0 seconds when the engine speed is above 1500 RPM, it will be stored in the combi-processor in the instrument cluster. If this condition occurs three times when the engine is running, the oil pressure warning will be activated and will not be cancelled even below 1500 RPM. The oil pressure warning will be cancelled when the oil pressure switch is closed for longer than 5 seconds at an engine speed above 1500 RPM, or when the ignition is switched off.

Test conditions
^ Engine oil level OK, Refer to Lubrication System Components, removing and installing, Refer to Fig. 1. Markings on oil dipstick
^ Oil Pressure Warning Lamp -K3- must light up for approximately 3 seconds when ignition is switched on
^ Engine oil temperature at least 80° C (radiator fan must have run once)





Test sequence
- Remove Oil Pressure Switch -F1- and screw into tester.
- Screw tester into oil filter bracket in place of oil pressure switch.
- Connect brown wire of tester to Ground (-).
- Connect LED test light VAG1527B using aux. cables from VAG1594A to battery positive (+) and oil pressure switch.
LED must not light up.
- If LED lights up, replace 1.4 bar Oil Pressure Switch -F1-.
When the LED does not light up:
- Start engine and run at idling speed:
At 1.2-1.6 bar LED must light up, otherwise replace oil pressure switch.
- Check oil pressure at different RPMs:
^ Idle: at least 2.0 bar
^ 2000 RPM: 2.7 to 4.5 bar
^ Above 2000 RPM: maximum 7.0 bar
If the specifications are not obtained:
- Repair mechanical damage (e.g. bearing damage).
- Replace oil filter bracket with pressure relief valve.
At higher engine speeds the oil pressure must not exceed 7.0 bar.
If the specification is exceeded:
- Check oil galleys.
- If necessary, replace oil filter bracket with pressure relief valve.