With Generic Scan Tool

Oxygen Sensor Heater For Oxygen Sensor Before Three Way Catalytic Converter (TWC), Checking

NOTE: When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold plated terminals.

Recommended special tools and equipment
- VAG1526 multimeter or VAG1715 multimeter
- VAG1594 connector test kit
- Wiring diagram

Test Requirements






- The respective fuses of Heated Oxygen Sensor (HO2S) -G39- must be OK.
- Ignition switched off.







- Unscrew protective cover (arrows) and disconnect 6-pin harness connector (black) -1- to Heated Oxygen Sensor (HO2S) -G39- before catalytic converter.







- Set multimeter for resistance measurement and connect it to terminals 3 + 4 at connector for oxygen sensor. Check oxygen sensor heater for continuity.

Specified value: 2.5...10 ohms(at room temperature)

If an open circuit is found in the oxygen sensor heater:
- Replace Heated Oxygen Sensor (HO2S) -G39- Bank 1 before catalytic converter, item 8
- Erase DTC memory of Engine Control Module (ECM), Diagnostic mode 4: Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
- Generate readiness code. Monitors, Trips, Drive Cycles and Readiness Codes

If oxygen sensor heater has continuity:
- Check voltage supply and wiring

Checking Voltage Supply And Wiring







- Set multimeter for voltage measurement and connect it to terminals 3+4 at connector to control module.
- Start engine, and let run at idle.
- Measure voltage supply
Specified value: oscillating between 0.0 and 12.0 V

If there is no voltage:
- Switch ignition off.
- Connect test box to control module wiring harness, connect test box for wiring test. Engine Control Module (ECM) is not connected. Test Box, Connecting For Wiring Test







- Check wire between test box and 6-pin connector for open circuit according to wiring diagram.
Terminal 4 + socket 5
Wire resistance: max. 1.5 ohms

If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).