Heater Check
Oxygen Sensor Heater For Oxygen Sensors Behind Three Way Catalytic Converter (TWC), Checking
Recommended special tools and equipment
- VAG1526A hand multimeter
- VAG1594A connector test kit
- VAG1598/31 test box
Test requirements:
- Fuse for oxygen sensor heater OK
- Ground (GND) connections at engine and transmission OK
- Fuel Pump (FP) Relay OK. With Generic Scan Tool
- Ignition switched off.
NOTE:
- Voltage for Oxygen Sensor (O2S) Heater 1 (behind Three Way Catalytic Converter (TWC)) -Z29- (bank 1, sensor 2) and Oxygen Sensor (O2S) Heater 2 (behind Three Way Catalytic Converter (TWC)) -Z30-(bank 2, sensor 2) is supplied via the Fuel Pump (FP) relay.
- Bank 1 = cylinder bank 1 in direction of travel, right; Bank 2 = cylinder bank 2 in direction of travel, left.
- When servicing terminals in harness connector of Heated Oxygen Sensor (HO2S), use only gold-plated terminals.
Work procedure
- Disconnect electrical 4-pin harness connector -1- at right from Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- and Oxygen Sensor (O2S) Heater 1 -Z29- (bank 1, sensor 2).
- Disconnect electrical 4-pin harness connector -2- from Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- and Oxygen Sensor (O2S) Heater 2 -Z30- (bank 2, sensor 2).
Checking internal resistance
- Connect multimeter between terminal 1 and 2 for resistance measurement.
- Specified value at room temperature: 2 ... 10 ohms
If specified value is not obtained:
- Replace respective oxygen sensor behind catalytic converter.
If specified value is obtained:
Checking voltage supply
- Connect multimeter between terminal 1 (B+) and 2 (Ground -GND-) for voltage measurement.
- Operate starter briefly.
- Specified value: approx. battery voltage
If there is no voltage:
- Connect multimeter for voltage measurement as follows:
Harness connector Measure to
Terminal
1 Engine Ground (GND)
- Operate starter briefly.
- Specified value: approx. battery voltage
- Switch ignition off.
If there is no voltage again:
- Check wire connection from harness connector terminal 1 to Fuel Pump (FP) Relay -J17- via fuse for open circuit according to wiring diagram.
- Specified value: Wire resistance max 1.5 Ohms
- If necessary, repair wire connection.
If voltage supply is OK:
Check Ground (GND) activation
- Connect multimeter for voltage measurement as follows:
Harness connector Measure to
Terminal
2 B+
- Operate starter briefly.
- Specified value: approx. battery voltage, possibly fluctuating
- Switch ignition off.
If specified value is not obtained:
- Connect test box to wiring harness of Engine Control Module (ECM); ECM is not connected. Test Box, Connecting For Wiring Test
- Check the following wire connections for open circuit according to wiring diagram:
- Oxygen Sensor (O2S) heater -Z29- bank 1 behind catalytic converter:
Harness connector Test box
Terminal Socket
2 63
- Oxygen Sensor (O2S) heater -Z30- bank 2 behind catalytic converter:
Harness connector Test box
Terminal Socket
2 6
- Specified value: Wire resistance max 1.5 Ohm
- Also check wires for short circuit to B+ and Ground (GND).
- Specified value: infinity Ohms (no continuity)
- If necessary, repair wire connection.
If no malfunctions are detected:
- Replace Engine Control Module (ECM).
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1 - Check DTC memory, See "Mode 3: Check DTC memory". Diagnostic Mode 3: Check DTC Memory
2 - If necessary, erase DTC memory, See "Mode 4: Reset/erase diagnostic data". Diagnostic Mode 4: Reset/Erase Diagnostic Data
3 - Generate readiness code. Readiness Code, Generating
- End diagnosis and switch ignition off.