Overview - Oxygen Sensors And Exhaust Temperature Control

Fig 1: Exhaust Sensor Overview

Courtesy of AUDI OF AMERICA, LLC

1. SCR - Catalytic Converter
   • SCR means: Selective Catalytic Reduction
2. Exhaust Gas Temperature Sensor 4 -G648-
   • 45 Nm
   • Removing and installing. Refer to EXHAUST TEMPERATURE CONTROL OVERVIEW .
   • Coat the thread with hot bolt paste; hot bolt paste. .
3. Particulate Filter
   • Removing and installing. Refer to PARTICULATE FILTER, REMOVING AND INSTALLING .
4. Primary Catalytic Converter
5. Exhaust Gas Temperature Sensor 3 -G495-
   • 45 Nm
   • Removing and installing. Refer to Exhaust Gas Temperature Sensor 3 -G495-, REMOVING AND INSTALLING .
   • Coat the thread with hot bolt paste; hot bolt paste. .
6. Catalyst Temperature Sensor 1 -G20-
   • 45 Nm
   • Installed only vehicles with engine code CATA (not installed on all vehicles)
   • Removing and installing. Refer to Catalyst Temperature Sensor 1 -G20-, REMOVING AND INSTALLING .
   • Coat the thread with hot bolt paste; hot bolt paste. .
7. Exhaust Gas Temperature Sensor 2 -G448-
   • 45 Nm
   • Installed only on vehicles with engine code CATA
   • Removing and installing. Refer to Exhaust Gas Temperature Sensor 2 -G448-, REMOVING AND INSTALLING .
   • Coat the thread with hot bolt paste; hot bolt paste. .
8. Nut
   • 2.5 Nm
9. NOx Sensor -G295-
   • 50 Nm
   • Removing and installing. Refer to NOx Sensor -G295-, REMOVING AND INSTALLING .
10. Heated Oxygen Sensor -G39- with Oxygen Sensor Heater -Z19-
    • 50 Nm
    • Coat new oxygen sensors with an assembly paste
    • On a used heated oxygen sensor, only the thread may be coated with hot bolt paste. .
    • Assembly paste or hot bolt paste must not get into the slits on the oxygen sensor body.
    • Removing and installing. Refer to Heated Oxygen Sensor -G39- WITH Oxygen Sensor Heater -Z19-, REMOVING AND INSTALLING .
11. Turbocharger
    • Removing and installing. Refer to TURBOCHARGER, REMOVING AND INSTALLING .
12. Exhaust Gas Temperature Sensor 1 -G235-
    • 45 Nm
    • Removing and installing. Refer to Exhaust Gas Temperature Sensor 1 -G235-, REMOVING AND INSTALLING .
    • Coat the thread with hot bolt paste. .
13. Differential Pressure Sensor -G505-
    • Pressure line to particulate filter 45 Nm
    • With two pressure pipes.
    • Removing and installing. Refer to Differential Pressure Sensor -G505-, REMOVING AND INSTALLING .
    • After replacing, perform an adaptation.
14. Nut
    • 3.5 Nm
15. Pressure Lines for the Differential Pressure Sensor -G505-
    • Pressure lines on the particulate filter: 45 Nm
    • Secure with hose clamps appropriate for the model type
16. NOx Sensor 2 -G687-
    • 50 Nm
    • Removing and installing. Refer to NOx Sensor 2 -G687-, REMOVING AND INSTALLING .
17. Nut
    • 3.5 Nm

Fig 2: Disconnect Connector -5-

Courtesy of AUDI OF AMERICA, LLC

3 -

NOx Sensor 2 -G687-

Reducing Agent Injector -N474-, Removing and installing. Refer to Reducing Agent Injector -N474-, REMOVING AND INSTALLING .