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With Manufacturer's Scan Tool



Heated Oxygen Sensor (HO2S) and Oxygen Sensor (O2S) control before TWC, checking

Special tools and equipment
- VAG1551 or VAG1552 Scan Tool (ST) with VAG1551/3 adapter cable
- VAG1598/22 test box
- Multimeter US1119 (Fluke 83 or equivalent)
- VW1594 connector test kit
- Wiring diagram

Checking conditions
- Engine coolant temperature at least 85°C (185°F) See VAG1551 scan tool function 08, display group 004, display field 3


Checking function
- Connect VAG1551 or VAG1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (with engine running at idle), Testing and Inspection

Indicated on display

Rapid data transfer HELP
Select function XX

- Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.

Indicated on display

Read Measuring Value Block HELP
Input display group number XXX

- Press buttons -0-, -3- and -2- to input display group number 32 (032), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)

Read Measuring Value Block 32 ->
1 2 3 4

- Check learning values for Oxygen Sensor (O2S) control before TWC (display fields 1- 4):

Display Group 32:






If the specifications are attained:
- Change to display group 33 as follows:
- VAG1551: Press -3- button
- VAG1552: Press Up arrow button

Indicated on display (1-4 = display fields)

Read Measuring Value Block 33 ->
1 2 3 4

- Check Oxygen Sensor (O2S) control before TWC (display fields 1-4):

Display Group 33:






If the specifications are attained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06, and press -0- button to confirm input.
- Switch ignition off.

Continuation
If the value in either display field 1 or 3 is NOT OK, or if the value does not fluctuate by at least 2%:
- Road test to condition oxygen sensor(s) (eliminate possible contamination) and repeat test.

WARNING!
When driving or riding in an airbag-equipped vehicle, NEVER hold scan tool or other test equipment in your hands or lap while in motion. Objects between you and airbag increase the risk of injury in an accident.
During a test drive in an airbag-equipped vehicle, test equipment must always be fastened to and operated from the rear seat by a second technician.

If the value in either display field 1 or 3 is still NOT OK, or if it still does not fluctuate by at least 2%:
- Check (O2S) heater(s) before (TWC). Oxygen Sensor Heater For Oxygen Sensors Before Catalytic Converter, Checking

If the value in either display field 1 or 3 remains constant:
- Check oxygen sensor voltage(s) (display fields 2 and 4).
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.
- Switch ignition off.

Evaluation of display group 32





Evaluation of display group 33, display fields 2, 4





HO2S reference voltage (banks 1, 2), checking
- Disconnect 4-pin connector for respective HO2S.




Heated Oxygen Sensor -G39- Bank 1, black connector (arrow)




Heated Oxygen Sensor -G108- Bank 2, black connector (arrow)






- Connect multimeter US1119 (Fluke 83 or equivalent) between harness connector terminals 3 and 4 (to ECM), using adapter cables from VW1594 connector test kit.
- Start engine and measure voltage.
Specified value: 0.40-0.50 volts
- Switch ignition off.

If voltage is NOT OK:
- Check HO2S wiring.
- Bank 1, sensor 1.
- Bank 2, sensor 1.

If voltage is OK:
- Replace respective Heated Oxygen Sensor (HO2S).
- Heated Oxygen Sensor -G39- Bank.
- Heated Oxygen Sensor -G108- Bank 2.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code. [1][2][3]Output Diagnostic Test Mode (DTM) (Function 03)

HO2S wiring, bank 1, sensor 1, checking





- Connect VAG1598/22 test box to ECM harness connector.






- Disconnect 4-pin connector (black) for HO2S -G39- (arrow).






- Check wiring for open circuit between ECM/test box and 4-pin HO2S harness connector (to ECM).
Connector terminal 3 to ECM/test box socket 25
Connector terminal 4 to ECM/test box socket 26
Specified value: max. 1.5 Ohms

- Check wiring for short circuits between terminals of 4-pin connector, and ECM/test box.
Connector terminal 4 to ECM/test box socket 25
Specified value: Infinity Ohms

- Check wiring for short circuits to wiring harness shielding.
Connector terminal 4 to ECM/test box socket 14
Connector terminal 3 to ECM/test box socket 14
Specified value: Infinity Ohms

If wiring is OK:
- Replace Motronic ECM -J220-. Service and Repair

HO2S wiring, bank 2, sensor 1, checking





- Connect VAG1598/22 test box to ECM harness connector.






- Disconnect 4-pin connector (black) for HO2S -G108- (arrow).






- Check wiring for open circuit between ECM/test box and 4-pin HO2S harness connector (to ECM).
Connector terminal 3 to ECM/test box socket 39
Connector terminal 4 to ECM/test box socket 40
Specified value: max. 1.5 Ohms

- Check wiring for short circuits between terminals of 4-pin connector, and ECM/test box.
Connector terminal 4 to ECM/test box socket 39
Specified value: Infinity Ohms

- Check wiring for short circuits to wiring harness shielding.
Connector terminal 3 to ECM/test box socket 14
Connector terminal 4 to ECM/test box socket 14
Specified value: Infinity Ohms

If wiring is OK:
- Replace Motronic ECM -J220-. Service and Repair

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