Oxygen Sensor Heater Behind Catalyst

Oxygen Sensor (O2S) Heater Behind TWC, Checking


NOTE:
- Connector for Oxygen Sensor (O2S) heater (behind TWC) -Z29- (bank 1, sensor 2): 4-pin, green
- Connector for Oxygen Sensor (O2S) 2 (behind TWC) -Z30- (bank 2, sensor 2): 4-pin, brown


Required special tools and test 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

Test requirements
- Fuse for Oxygen Sensor (O2S) heater OK
- Engine Coolant Temperature (ECT) at least 80 °C (176 °F)

Checking
- Connect VAG1551 or VAG1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (with engine running at idle). [1][2]Scan Tool Connecting and Initial Checks

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-, -4- and -0- to input display group number 40 (040), and press -Q- button to confirm input.

Indicated on display (1-4 = display fields)


Read Measuring Value Block 40 ->
1 2 3 4


- Compare display and specified values (display fields 3 and 4):

Display Group 40:

If displayed values are OK (as specified):
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06, and press -Q- button to confirm input.
- Switch ignition off.

Continuation
- Disconnect 4-pin connector for respective Oxygen Sensor (O2S) behind Three Way Catalytic Converter (TWC).







- Connect multimeter US1119 (Fluke 83 or equivalent) between HO2S connector terminals 1 and 2, using VW1594 connector test kit.
- Measure resistance.
Specified value: 0.00-19.9 Ohms

If resistance is NOT OK:
- Replace respective Oxygen Sensor (O2S) behind TWC.

If resistance is OK:
- Switch multimeter to 20 VDC measuring range.







- Connect multimeter between harness connector terminals 1 and 2 (to ECM), using VW1594 connector test kit.
- Measure voltage supply and check display in display group 40, display field 4.

If display = Htg.ac.ON:
- Specified value: 11.0-14.5 volts

If display is switching between "Htg.ac.ON" and "Htg.ac.OFF"
- Specified value: 0.0-12.0 volts (oscillating)

If there is no voltage:







- Connect multimeter between harness connector terminal 1 (to ECM) and vehicle Ground, using VW1594 connector test kit.
Specified value: 11.0-14.5 volts

If there is still no voltage:
- Check wiring between terminal 1 and relay panel using appropriate wiring diagram.

If there is voltage:







- Connect multimeter between harness connector terminal 2 (to ECM) and Battery Positive Voltage (B+), using VW1594 connector test kit.
- Measure voltage supply and check display in display group 40, display field 4

If display = Htg.aC.ON:
- Specified value: 11.0-14.5 volts

If display switches between "Htg.aC.ON" and "Htg.aC.OFF:"
- Specified value: 0.0-12.0 volts (oscillating)
- Switch ignition off.

If specified value is not attained:
- Connect VAG1598/22 test box to ECM harness connector. Connecting VAG 1598/22 Test Box







- Check wiring for open circuit between ECM/test box and 4-pin O2S harness connector (to ECM).
- Connector terminal 2 to ECM/test box socket 28
- Specified value: max. 1.5 Ohms

If wiring is OK:
- Replace ECM -J220-.
- Carry out adaptation of throttle valve control module to ECM.
- Check readiness code. If Diagnostic Trouble Code (DTC) memory has been erased, or ECM was disconnected, generate new readiness code. Audi Drive Cycle/Readiness Code