Water in Common rail Diesel fuel system

Most common rail engine failures can be prevented. Read on to find out how you can help your common rail diesel stand the test of time.

Water is the most damaging fuel contaminant in a common rail fuel system, it creates a lack of lubrication in the fuel system which in turn can prematurely wear your high pressure pump and injectors.

We see at least 3 water in diesel fuel related failures per week, sometimes more, particularly in common rail systems.

The high pressure pump and injectors used in a diesel common rail vehicle rely on good quality fuel, they have a high failure rate when water contamination is present.

Water contamination in diesel fuel pumps

  • Water in Common rail Diesel fuel system
  • Water in Common rail Diesel fuel system
  • Water in Common rail Diesel fuel system
  • Water in Common rail Diesel fuel system

Options for water in fuel prevention

There is really no way to filter water, it can possibly be seperated but not filtered.

A secondary filter in our opinion would restrict the fuel flow in your engine and is not something we recommend. 

 Preventative warning systems for water are the option that we believe is most effective however it is not a set and forget device. 

A waterscan kit is something we have developed  to try and combat water related failures in your common rail fuel system – it alerts you via a light or buzzer on your dash when it detects water is present in  your fuel. 

the most common failure symptoms from water contamination

  • Vehicle cuts out altogether – stops dead
  • Vehicle runs rough
  • Blowing excessive smoke 
  • Presents with high pressure leak codes
  • Vehicle goes into limp mode


When or if the light/buzzer goes off  - this is the bit where you come in! 

  1. Stop your car immediately (even a small amount of water in the fuel system can do huge damage) 
  2. Drain the water from the waterscan unit using the drain plug on the bottom of the unit. 
  3. Once drained and plug and been reinstalled, prime fuel system using factory primer pump to start the vehicle 
  4. If water has been collected you should look at draining / cleaning your fuel tanks and getting your fuel system checked. 

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