Diesel fuel filter can seperate water from fuel. If water more than specified amount is detected by "water sensor" installed at the bottom of fuel filter, "Fuel warning lamp" on cluster turns ON.
Especially for high pressure pump or injectors of common rail diesel engine is fatal. because water causes poor lubrication and corrosion in such accurate devices, furthermore, it leads engine hesitation. In order to prevent this harsh condition to engine, "Water warning lamp" turns ON to let driver relief the gathered water from the filter and engine power generation is limited.
If sensing prove of water sensor contacts with water, impressed voltage on prove is grounded to chassis ground, then 12V is outputted from signal line. With this method, ECM recognizes the amount of water.
