LEMON Manuals: Even more car manuals for everyone: 1960-2025
Home >> Volkswagen >> 2014 >> Golf TDI, Standard Trans >> Repair and Diagnosis >> Engine Performance >> Fuel Delivery >> 2.0L - Diesel Fuel Injection - Engine Code(S): CJAA >> 23 Diesel Fuel Injection >> Description And Operation >> Diesel Direct Fuel Injection System Overview
April 5, 2026: LEMON Manuals is launched! Read the announcement.

Diesel Direct Fuel Injection System Overview

WARNING:
  • Follow the guidelines for a clean working environment when working on the fuel system. Refer to CLEAN WORKING CONDITIONS .
  • Always follow these rules before and during work.
  • If fuel system components between the fuel tank and high pressure fuel pump were removed or replaced, the fuel system must be filled in order to bleed it. Refer to FUEL SYSTEM, FILLING AND BLEEDING . (Never let the high pressure pump run dry).
Fig 1: Identifying Diesel Direct Fuel Injection System Overview
GWWN23-10272Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
  1. Fuel Tank 
    • With the transfer fuel pump -G6-.
  2. Fuel Filter 
  3. Auxiliary Fuel Pump -V393- or fuel pump 2 -V277- 

    Removing and installing, refer to AUXILIARY FUEL PUMP -V393- OR FUEL PUMP 2 -V277- .

  4. Filter 
  5. Fuel Temperature Sensor -G81- 
  6. High Pressure Pump 
  7. Fuel Metering Valve -N290- 
    • Must not be removed.
  8. Fuel Pressure Regulator Valve -N276- 
  9. Fuel Rail (High Pressure Reservoir) 
  10. Fuel Pressure Sensor -G247- 
  11. Pressure Retention Valve 
    • The retention valve always maintains a residual pressure (control quantity) of approximately 10 bar in the fuel return lines.
    • The fuel injectors need this control quantity to function correctly.
    • The retention valve can be replaced only with the complete fuel return lines.
    • The engine must run at idle for approximately two minutes after replacing, to bleed the fuel system.
    • Checking the pressure retention valve. Refer to PRESSURE RETENTION VALVE IN FUEL RETURN LINE, CHECKING .
  12. Fuel Injector (Piezo Injectors) 
    • Cylinder 1 fuel injector -N30-.
    • Cylinder 2 fuel injector -N31-.
    • Cylinder 3 fuel injector -N32-.
    • Cylinder 4 fuel injector -N33-.
    • Removing and installing, refer to FUEL INJECTOR .