Group 30: Electrical system
Diagnostic Trouble Codes
MID 128, PID 97 Water in fuel
MID 128: Engine control unit FMI 0:
The sensor value is valid but above the normal working range.
FMI 3:
The voltage exceeds the normal value or is short circuited to higher voltage.
FMI 4:
The voltage is less than the normal value or is short circuited to lower voltage.
FMI
Fault code explanation
0
Water in fuel
3, 4
Faulty sensor / Faulty monitor circuit
Fault indication DCU:
Engine warning in DCU display
CIU:
Flash code
Flash code Electrical fault: 2.9 Value fault:
2.1
Symptom None
water in fuel
splice
Circuit description A monitor is located in the water trap under the fuel filter. Its task is to detect whether there is water in the fuel. The monitor senses the resistance between two pins, wich are in contact with the fuel. When there is no water in the fuel, the resistance is very high. If there is any water in the fuel, the resistance falls. At a threshold resistance (water has been detected), the monitor’s output signal (yellow cable) to the engine control unit pin B8 will be pulled down to zero.
43
