High Fuel Pressure, Reducing
Special tools and workshop equipment required
- Vehicle Diagnostic Tester
There is a risk of injury because the fuel is under very high pressure.
- The fuel injection system is separated into a high-pressure section, a maximum of about 120 bar (1, 740 psi) and a low-pressure section of about 4 to 7 bar (58 to 101 psi).
- Before opening high pressure components, for example removing the high pressure pump, fuel rail, fuel injectors, fuel pipes or Fuel Pressure Sensor -G247-, the fuel pressure in the high pressure area must be reduced to a residual pressure of approximately 7 bar (101 psi). The procedure for this is as follows.
High Fuel Pressure, Reducing:
-- Turn on the ignition and select the following menu items on the Vehicle Diagnostic Tester:
- 01 - Engine electronics
- Guided functions
- 01 - Removing fuel high pressure
- The fuel pressure reduces to a specified value.
-- Switch off the ignition again.
The fuel rail will continue to be filled with fuel, but it will no longer be under high pressure.
Do not let fuel come into contact with skin.
- Wear protective eyewear and clothing when opening the fuel system.
- Lay clean cloths around the connection before opening the high pressure area to collect any fuel that leaks out.
-- After reducing fuel pressure, place a clean cloth around the connection and open the high pressure system immediately. Escaping fuel must be absorbed.
If the high pressure system is not opened immediately, the pressure will increase because of post-heating.
The ignition can no longer be switched on, otherwise the pressure will increase again.
Final Procedures:
-- Delete the DTC memory and generate a readiness code in the engine control module in "Guided Functions" using the Vehicle Diagnosis Tester.