Checking HO2S Control Signal

Location of Heated Oxygen (HO2S) sensor and harness connection. See COMPONENT LOCATIONS .

1. Disconnect harness connector 1 for HO2S signal wire. See Figure. Switch DVOM to 2 volt (DC) measuring range. Connect multimeter (using adapter cables from connector test kit VW 1594) between ECM harness connector and engine ground. Switch ignition ON. Voltage must be 400-500 millivolts.
2. If voltage is incorrect, connect (VAG 1598) test box (using VAG 1598/5 adapter cable) to ECM harness connector. See CONNECTING VAG 1598 TEST BOX .
NOTE: ECM harness connector is not connected.
3. Switch DVOM to resistance range. Check continuity between harness connector in engine compartment and test box terminal No. 28. Resistance must be 1.0 ohm maximum. If circuit is open, repair as necessary. See WIRING DIAGRAMS .
4. If circuit is NOT open, check continuity of ground connection between engine cylinder block and test box terminal No. 10. Resistance must be 1.0 ohm maximum. If circuit is open, repair as necessary. See WIRING DIAGRAMS .
5. If circuit is open, perform necessary repairs. If circuit is NOT open, switch DVOM to 10-Amp (DC) measuring range. Connect additional test cable (VW 1315 A/1) to harness connector position 2.