Control lamp of level of a brake liquid
The oil pressure in the Audi A4 engine is monitored by an oil pressure sensor in combination with an electronic logic unit in the combined instrument panel. In this regard, the signal is no longer given on the basis of only oil pressure, but in combination with data on the temperature of the coolant and the engine speed. Criteria for turning on the signal light:
- The engine is not running, the oil pressure sensor is closed.
- The coolant temperature is above 60°C, the engine speed is over 1500 rpm and the oil pressure switch is open.
- The coolant temperature is below 60°C, the speed is above 300 rpm and the oil pressure switch is open.
- At engine speeds above 5000 rpm, the activated oil pressure signal does not turn off (regardless of the position of the oil pressure switch).
- If, when the engine is running at a speed above 1500 / min, the oil pressure sensor remains open for more than 0.5 s, then this information is stored in the computer. If this condition occurs three times in a row, the warning signal is activated and does not turn off even if the speed drops. From the next ignition on, the countdown starts again.
Oil pressure switch
Four- and six-cylinder engines have different oil pressure sensors, the insulated parts of which have a different color to distinguish them:
- Black on oil pressure switch from 1.4 bar on four-cylinder engines.
- White at the oil pressure switch from 1.8 bar on six-cylinder engines.
Troubleshooting
If the signal light (sometimes with beep) lights up when the engine is running, you must stop immediately!
Stop the engine immediately and check the oil level. If everything is ok, then:
- Have your vehicle towed to prevent more serious damage due to lack of lubrication.
- As a next step, check the oil pressure.
- If the oil pressure is OK, then you can change the oil pressure sensor (In workshop).
- If, despite this, the lamp does not go out, then the cause is in the device.
Oil pressure sensor replacement
The wires to the oil pressure sensor and to the oil temperature sensor in a six-cylinder engine are connected in this plug (arrow) on the back of the left cylinder head.
On the left next to the crankshaft belt pulley in a six-cylinder engine is a sensor (1) oil temperature indicator and oil pressure sensor (2).
1. Buy the desired oil pressure sensor with black or white insulation and a new o-ring to it.
2. Tighten the oil pressure switch only 25 Nm.
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