Before Three Way Catalytic Converter
OXYGEN SENSOR HEATING, BEFORE THREE WAY CATALYTIC CONVERTER, CHECKING
Special tools, testers and auxiliary items
- VAG 1551/1552 scan tool with VAG 1551/3 adapter cable
- VAG 1598/18 test box
- Multimeter (Fluke 83 or equivalent)
- Connector test kit VW 1594
- Wiring diagram
Test conditions
- Fuse 18 OK
Test sequence
- Engine running at idle
- Connect VAG 1551/1552 scan tool and select "Engine Electronics" address word 01. Refer to "On-Board Diagnostics II With VAG 1551". 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 -1-, -2- and -0- to input display group 120 and press -Q- button to confirm input.
Indicated on display (1-4 = Display fields)
Read Measuring Value Block 120 ->
1 2 3 4
- Check the resistance value for oxygen sensor heating before three way catalytic converter (display field 3).
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.
Relevance of values in 8-digit number block
Continuation
- Separate 4-pin connector -1- (black) to HO2S -G39- (before three way catalytic converter).
- Connect multimeter with test leads from VW 1594 to measure resistance at terminals 1 and 2 on connector to HO2S.
- Check the resistance value.
Specification: 0.0-24.2 Ohms
If the specification is not attained:
- Replace HO2S -G39- (before three way catalytic converter).
If the specification is attained:
- Check relevance table for value of O2S control status, display group 120, display field 4, 1st position from left.
- Set multimeter to voltage measurement range.
- Connect multimeter using test leads from VW 1594 to measure voltage between terminals 1 and 2 (ECM side of harness connector).
- Measure the voltage supply.
When display = 1: specification is 11.0-14.5 volts
When display = alternately 0 and 1: specification is fluctuating between 0.0-12.0 volts
If no voltage is present:
- Connect multimeter with test leads from VW 1594 to measure voltage between terminal 1 (ECM side of harness connector) and vehicle Ground (GND).
Specification: 11.0-14.5 volts
If again no voltage is present:
- Check wiring from terminal 1 to relay panel according to wiring diagram.
If voltage was present:
- Check relevance table for value of O2S control status, display group 120, display field 4, 1st position from left.
- Connect multimeter using test leads from VW 1594 between terminal 2 (ECM side of harness connector) and battery positive (B+).
When display = 1: specification is 11.0-14.5 volts
When display = alternately 0 and 1: specification is fluctuating between 0.0-12.0 volts
- Switch ignition off.
If no voltage is present:
- Connect VAG 1598/18 test box to ECM wiring harness.
- Check wiring between test box and 4-pin connector for open circuit according to wiring diagram.
Terminal 2 and test box socket 12
Resistance: maximum 1.5 Ohms
If no wiring malfunction is detected:
- Replace Engine Control Module (ECM) -J220-.
- Read the readiness code. If DTC memory has been erased, repair must be verified via appropriate display group See Readiness code, creating. Refer to "On-Board Diagnostics II With VAG 1551". Testing and Inspection