Sensor and Control Check

Oxygen Sensor and Oxygen Control (Before CAT), Checking

Special tools and equipment
- VAG 1551/1552 Scan Tool using VAG 1551/3 adapter cable
- VAG 1598/18 Test Box
- Fluke 83 multimeter (or equivalent)
- VW 1594 Adapter set
- Wiring diagram

Requirement
- Engine Coolant Temperature 80 °C minimum

Functional check
- Connect VAG 1551 (VAG 1552) Scan Tool. Refer to Scan Tool Testing/VAG 1551 Scan Tool. Testing and Inspection
- With engine idling, press buttons -0- and -1- to select "Engine electronics" address word 01.

Display will appear as shown


Rapid data transfer HELP
Select function XX


- Press buttons -0- and -8- to select "Read measuring value block".
- Press -Q- button to enter selection.

Display will appear as shown


Read measuring value block HELP
Input display group number XXX


- Press buttons -0-, -2- and -5- to select "Display group number 25".
- Press -Q- button to enter selection.


Display will appear as shown (1 to 4 = Display fields)


Read measuring value block 25 ->
1 2 3 4

- Check Oxygen control Specifications (before cat). See Display fields 1 to 3

Display Group 15:

Continuation
If the specification in Display field 1 is not obtained, or the value does not fluctuate at least 2%
- Road-test vehicle to reduce possible build-up on Oxygen sensor and repeat check.

If the specification in Display field 1 is not obtained even after a road test, or the value does not fluctuate at least 2 %:
- Check Oxygen sensor heating. Heater Check

If the value displayed in Display field 1 remains constant:
- Press -C- button.
- Press -1-, -1- and -5- to select "Display group number 115".
- Press -Q- button to enter selection.

Display will appear as shown (1 to 4 = Display fields)


Read measuring value block 115 ->
1 2 3 4


- Note Oxygen sensor Voltage in Display field 3.

Display Group 115:

- Press -> button.
- Press buttons -0- and -6- to select "End output".
- Press -Q- button to enter selection.
- Switch ignition off.

Evaluating display group 25

Display Group 25:

Evaluating display group 115







Relevance of figures in 8 digit number block







Basic Voltage, checking







- Disconnect (black) 4-pin harness connector to Oxygen sensor (before cat) -G39- -1-.







- Connect multimeter between terminals 3 + 4 using jumper wires from VW 1594 adapter kit.
- Start engine and measure basic voltage.
specification: 0.40 to 0.50 Volts
- Switch ignition off.

If specification not obtained:
- Check Oxygen sensor wiring.

If specification obtained:
- Replace Oxygen sensor (before cat) -G39-.

Oxygen Sensor Wiring, Checking







- Connect VAG 1598/18 Test Box to ECM harness connector.







- Disconnect (black) 4-pin harness connector to Oxygen sensor (before cat) -G39- -1-.







- Check wiring between Test Box and 4-pin ECM connector for open circuit using wiring diagram, connect as follows:
terminal 3 + socket 42
terminal 4 + socket 20
- wire resistance: 1.5 Ohms

- Check wires at 4-pin connector for shorting to one another.
terminal 4 + socket 42
- specification: infinity Ohms

- Check shielding for short to sensor wiring using wiring diagram, connect as follows:
terminal 4 + socket 56
terminal 3 + socket 56
- specification: infinity Ohms

If wiring OK:
- Replace ECM -J220-.
- Perform Basic setting.
- Read-out Readiness code. Refer to Monitors, Trip and/or Drive Cycle (Readiness Codes)/Readiness Code Checking. Testing and Inspection

If DTC memory was erased, create new Readiness code. Refer to Monitors, Trip and/or Drive Cycle (Readiness Codes)/Readiness Code Generating Testing and Inspection