Sensor and Sensor Control

Oxygen Sensor and Oxygen Sensor Control Before Three Way Catalytic Converter (TWC), Checking

Special tools and shop equipment
- Fluke 83 (or equivalent) A
- VAG1594A
- VAG 1598/31
- VAS5051/1 with VAS5051/1 - or
- VAG1551 with VAG1551/3B

NOTE:
- For the defined troubleshooting procedure, it is possible to switch off the oxygen sensor control by selecting Display Group 99 in "Basic Setting" mode and to switch it on again by selecting Display Group 99 in "Read Measuring Value Block" mode.
- After selecting Display Group 99 (either in "Basic Setting" mode or in "Read Measuring Value Block" mode) it is possible to switch back and forth between function 04 ("Basic Setting") and function 08 "Read Measuring Value Block") by pressing buttons 4 and 8 on VAG1551 scan tool.
- When exiting the "Basic Setting" mode (function 04) the oxygen sensor control is automatically switched on again.

Test conditions
- Perform road test and do not erase DTC memory.
- Coolant temperature at least 85 °C (Display group 004, display field 3)

Checking function
- Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 scan tool and select engine electronics control module by entering address word "01 ". When doing this the engine must be at idle. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAS 5051/ VAG 1551 Scan Tool" Testing and Inspection

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

NOTE: During the basic setting the Evaporative Emission (EVAP) canister purge regulator valve -N80 is closed and the A/C compressor is switched off

Indicated on display

Basic Setting
Input display group number XXX

- Press buttons -0-, -3- and -0- to select "display group number 030" and confirm entry with -Q- button.

Indicated on display: (1 - 4 = display fields)

System in Basic Setting 30 ->
1 2 3 4

- Check oxygen sensor status in display fields 1 to 4.

NOTE:

Display Group 030:

Significance 0f 3 digit indication in Display Group 30

Checking oxygen sensor adaptation and oxygen sensor control
- Connect vehicle diagnostic, testing and information system VAS5051 or VAG1551 and select engine electronics control module by entering address word "01". When doing this the engine must be idling. Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAS 5051 / VAG 1551 Scan Tool" Testing and Inspection

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -4- to select function "Basic Setting" and confirm entry with -Q- button.

NOTE: During the basic setting the Evaporative Emission (E VA P) canister purge regulator valve -N80 is closed and the A/C compressor is switched off.

Indicated on display

Basic Setting
Input display group number XXX

- Press buttons -0-,-3- and -3- to select "display group number 033" and confirm entry with -Q- button.

System in Basic Setting 33 ->
1 2 3 4

- Check oxygen sensor control in display fields 1 to 4:

Display Group 033:

- Press button -C-
- Press button -0-,-3- and -2- to select "display group number 033" and confirm entry with -Q- button.

Indicated on display (1-4 = display fields)

System in Basic Setting 32 ->
1 2 3 4

- Check oxygen sensor control in display fields 1 to 4:

Display Group 032:

if the specified values in displayed fields 1 and/or 3 do not match the specifications, or if the readout does not fluctuate by at least 2%:

- Check oxygen sensor heater
- Check oxygen sensor signal wire and activation.
- Check intake system for leaks and eliminate false air. Testing and Inspection
- Check fuel pressure regulator. Testing and Inspection
- Fuel return line kinked or plugged.
- Press -> button.
- Press button -0- and -6- to select function "End Output" and confirm with -Q- button.
- Switch ignition off.

Evaluation display group 032

Display Group 032:

Evaluation display group 033