Fuel Heater DDE5.0/5.1

The fuel heater is integrated in the fuel filter and is activated depending on the temperature and pressure in the fuel filter. Pressure switches and thermostats are also integrated in the fuel filter. The fuel heater only works with the ignition switched on.

The fuel heater is switched on in the case of:

• Fuel pressure > 6 bar AND
  
• Fuel temperature < 2 °C
  

The fuel heater is switched off again in the case of:

• Fuel pressure < 5.5 bar for a duration of > 5 min OR
  
• Fuel temperature > 12 °C OR
  
• During the starting process: if the electronics in the fuel filter detect a battery voltage < 7.5 V for longer than 0.2 s
  

Troubleshooting

The fuel heater is not activated by the DDE control unit. However, the fuel heater reports a detected filter blockage via the signal DIAG_DKH to the DDE control unit. The DDE control unit then stores the fault.