Diesel Emissions Fluid Level Sensor: Description and Operation
GF14.40-D-3060HU Component Description For Fill Level Sensor
- with CODE (MG5) Engine OM 642 DE 30 LA, 140 kW (190 hp) 3800 rpm
- with CODE (MH1) Low-emission engine EPA 10/CARB
- with CODE (ZU7) National version for Canada
- with CODE (MG5) Engine OM 642 DE 30 LA, 140 kW (190 hp) 3800 rpm
- with CODE (MH1) Low-emission engine EPA 10/CARB
- with CODE (ZU8) National version for USA
30 AdBlue(R) tank
32 AdBlue(R) extraction tank
70 Upper measuring electrode
71 Center measuring electrode
72 Lower measuring electrode
B152 AdBlue(R) tank fill level sensor
R51b1 AdBlue(R) tank temperature sensor
Location
The AdBlue(R) tank fill level sensor is located together with the AdBlue(R) tank temperature sensor and the AdBlue(R) removal tank in the AdBlue(R) tank.
Task
The AdBlue(R) tank fill level sensor detects the fill level of the AdBlue(R) reducing agent in the AdBlue(R) tank.
Design
The AdBlue(R) tank fill level sensor is fitted with 3 measuring electrodes. One electrode on the lower end of the AdBlue(R) tank fill level sensor serves as a common reference electrode.
Function
The AdBlue(R) control unit (N141) actuates the measuring electrodes one after another by means of a pulse width modulated (PWM) signal.
If all measuring electrodes and the reference electrode are wet by the AdBlue(R) reducing agent, the AdBlue(R) control Task unit detects that the AdBlue(R) tank is "Full" based on signals from the AdBlue(R) tank fill level sensor. if the center and the lower measuring electrode and the reference electrode are wet by the AdBlue(R) reducing agent, the AdBlue(R) control unit detects that the fill level is between "full" and "reserve". If only the lower measuring electrode and the reference electrode are wet by the AdBlue(R) reducing agent, the AdBlue(R) control unit detects that the fill level is "Reserve".
If only the reference electrode is moistened with AdBlue(R) reducing agent, the fill level is "Empty".
The AdBlue(R) control unit sends the corresponding fill level signal over the drive train sensor CAN (CAN I) to the CDI control unit (N3/30) and over the engine compartment CAN to the instrument cluster (A1).
Depending on the fill level (Full, Reserve or Empty), a message is issued by the instrument cluster which is supported in the case of fill level "Reserve" and fill level "Empty" by an acoustic signal.
After each fill level recognition, the possible range which can be achieved with the stocks of reducing agent available is determined by a computer model.
When the "Reserve" fill level is reached, the driver is informed with an audible and a message on the display (A1p1) that he should find a workshop and have the required maintenance work done.
If the "Empty" fill level is reached in the AdBlue(R) tank, a plausibility check on the "Empty" fill level is carried out using a computer model. If the plausibility check also results in an "empty" fill level, an audible signal is given, an entry is made in the fault memory of the control unit (CDI), and there is actuation of the CHECK ENGINE indicator lamp in the IC.A1e41 The driver then has up to 20 engine starts available, with an assumed trip distance of 32 kilometers or 20 miles in each case. The number of the still available starts is displayed in the instrument cluster. The vehicle can no longer be started after the last remaining "Start".
Fluctuations in the fill level due to particular driving situations are compensated by a damping function in the AdBlue(R) control unit.