Oxygen Sensor Heater Before Catalyst

Oxygen Sensor (O2S) heater before TWC, checking


NOTE:
- Connector for Oxygen Sensor (O2S) heater -Z19- (bank 1, sensor 1): 4-pin, black.
- Connector for Oxygen Sensor (O2S) 2 heater -Z28- (bank 2, sensor 1): 4-pin, black.


Required special tools and test equipment
- VAG 1551 or VAG 1552 Scan Tool (ST) with VAG 1551/3 adapter cable
- VAG 1598/22 test box
- Multimeter US 1119 (Fluke 83 or equivalent)
- VW 1594 connector test kit
- Wiring diagram

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

Checking
- Connect VAG 1551 or VAG 1552 scan tool and press buttons -0- and -1- to insert "Engine Electronics" address word 01 (with engine running at idle).Refer to "Scan tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1551/VAG 1552 Scan Tool" Connecting VAG 1551 Scan Tool

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 1 and 2):

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 (black) for respective Heated Oxygen Sensor (HO2S).







- Connect multimeter US 1119 (Fluke 83 or equivalent) between HO2S connector terminals 1 and 2, using VW 1594 connector test kit.
- Measure resistance.
Specified value: 0.0-19.9 Ohms

If resistance is NOT OK:
- Replace respective Heated Oxygen Sensor (HO2S).

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







- Connect multimeter between harness connector terminals 1 and 2 (to ECM), using VW 1594 connector test kit.
- Measure voltage supply and check display in display group 40, display field 2.

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

If display switches between "Htg.bC.ON" and "Htg.bC. 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 VW 1594 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 VW 1594 connector test kit.
- Measure voltage supply and check display in display group 40, display field 2.

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

If display switches between "Htg.bC.ON" and "Htg.bC.OFF":

Specified value: 0.0-12.0 volts (oscillating)
- Switch ignition off.

If there is no voltage:
- Connect VAG 1598/22 test box to ECM harness connector.Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/Connecting VAG 1598/22 Test Box" Connecting VAG 1598/22 Test Box







- Check wiring for open circuit between ECM/test box and 4-pin HO2S harness connector (to ECM).
- Connector terminal 2 to ECM/test box socket 27
- Specified value: max. 1.5 Ohms

If wiring is OK:







- Replace Motronic 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