Heated Oxygen Sensor and Oxygen Sensor Control, Checking
HEATED OXYGEN SENSOR AND OXYGEN SENSOR CONTROL, CHECKING
Special tools, testers and auxiliary items
- VAG 1551 Scan Tool (ST) or vehicle system tester VAG 1552 with VAG 1551/3 adapter cable
- VAG 1598/18 test box
- Multimeter (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagram
Checking conditions
- Coolant temperature at least 80 °C (176 °F)
- Exhaust system free of leaks between cylinder head and Three Way Catalytic Converter (TWC)
Functional check
- Connect VAG 1551 scan tool (VAG 1552) and select "Rapid data transfer" operating mode.
- Press buttons -0- and -1- to insert "Engine Electronics" address word 01. Carry out selection at idle. Refer to "On-Board Diagnostic". 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.
- Press -Q- button to confirm input.
Indicated on display
Read measuring value block HELP
Input display group number XXX
NOTE: If something different is indicated on the display:
See Scan tool operating instructions.
- Press -0-, -0- and -1- to input display group number 001.
- Press -Q- button to confirm input.
Indicated on display (1, 2, 3 and 4 = Display fields)
Read measured value block 1 ->
1 2 3 4
- Read oxygen sensor factor in display field 3.
Specification: display fluctuates around 1
If oxygen sensor factor does not fluctuate:
- Carry out road test to clean HO2S probe, then repeat check.
If the oxygen sensor factor specification is not attained:
- Check oxygen sensor heating. Oxygen Sensor Heating, Checking
If the displayed value remains constant:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06.
- Press -Q- button to confirm input.
- Switch ignition off.
- Continue check according to following table.
Checking basic voltage
- Separate 4-pin HO2S harness connector
- Start engine and run at idle speed.
- Connect multimeter to measure voltage at connector terminals 3 and 4 of connector.
Specification: Approx. 0.45 volts
- Switch ignition off.
If the specification is not attained:
- Check HO2S wiring.
Checking HO2S wiring
- Connect VAG 1598/18 test box to ECM wiring harness.
- Separate 4-pin HO2S harness connector.
- Check wiring for open circuits between test box and 4-pin connector, according to wiring diagram.
- Terminal 3+socket 42
- Terminal 4+socket 20
- Wire resistance: Max. 1.5 Ohms
- Check wires at 4-pin connector for shorts to one another.
- Terminal 1 and test box socket 20
- Terminal 1 and socket 42
- Terminal 2 and test box socket 42
- Terminal 2 and socket 20
- Terminal 3 and test box socket 20
- Specification: Infinity Ohms
- Check shielding for short to HO2S wiring according to wiring diagram.
- Terminal 3 and test box socket 56
- Terminal 4 and test box socket 56
- Specification: Infinity Ohms
If the specifications are not attained:
- Check wiring according to wiring diagram.
If no wiring malfunction is detected:
- Replace heated oxygen sensor G39.