Fuel Heating: Notes

Fig 1: Identifying Fuel Filter Heating Stamped Date

Courtesy of BMW OF NORTH AMERICA, INC.

1. Stamped date of manufacture in the format DD.MM.YY, in the example shown above 04 June 2007

The fuel heating unit is integrated in the fuel filter and is activated depending on the temperature and pressure in the fuel filter. Pressure and temperature switches 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