Diagnose
Status September 2003 (EvoBus-Service / AFT)
Page: 65 of 83
4.1.21
Oil pressure
The oil pressure is calculated every 10 ms. The calculated pressure is smoothed with a low-pass filter.
The characteristic curve of the oil pressure sensor integrated in the engine control unit is stored in the
control unit software. If the voltage of the oil pressure sensor is above 4.92 V or below 0.25 V for more
than 2 seconds, then the event "Fault measuring range exceeded or dropped below" is detected and the
fault code 1615 or 1616 is entered. A substitute value of 3.1 bar is used as the oil pressure. If the fault
debouncing time has not yet expired, however the voltage value is outside the limits, the last atmospheric
pressure calculated under valid conditions is retained.
In addition, the plausibility of the oil pressure sensor in the "Engine stopped" engine state is checked with
the signal of the atmospheric pressure sensor. With the engine at a standstill, the oil pressure and
atmospheric pressure must be approximately equal. If the pressure difference of both sensors is greater
than 100 mbar for at least 2 seconds, then the event "Oil pressure sensor: Signal implausible" is detected
and the fault code 1617 is entered. The test only takes place when both the oil pressure sensor and the
atmospheric pressure sensor show no fault electrically and the engine is stopped. The fault code is only
an indicator – no measures are taken as the result of this event.
In the case of an implausible oil pressure, the oil temperature is also classified as defective and the
substitute value is set (combination pressure/temperature sensor).
Characteristic curve: Oil pressure sensor
SEN - P oil (active, absolute): sensor code
Oil pressure [bar] = f(Sensor voltage [V])
O
il pressure
Voltage
