Oxygen Sensor Heater For Oxygen Sensors Before Catalytic Converter, Checking

Oxygen Sensor Heater For Oxygen Sensors Before Catalytic Converter, Checking







Recommended special tools and equipment
- V.A.G 1526A multimeter
- V.A.G 1594A connector test kit
- V.A.G 1598/31 test box

Test requirements:
- Fuse for oxygen sensor heating OK
- Ground (GND) connections at engine and transmission OK
- Fuel Pump (FP) Relay OK; checking. Fuel Pump (FP) Relay -J17- and Activation, Checking
- Ignition switched off.

NOTE:
- Voltage for Oxygen Sensor (O2S) Heater -Z19- (bank 1, sensor 1) and Oxygen Sensor (O2S) 2 Heater 2 -Z28- (bank 2, sensor 1) 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 oxygen sensor, use only gold-plated terminals.

Procedure







- Disconnect electrical 6-pin harness connector 2- at right from Heated Oxygen Sensor (HO2S) -G39- (before catalytic converter) and Oxygen Sensor (O2S) Heater -Z19- (bank 1, sensor 1).







- Remove coolant reservoir -2- (arrows)
- Disconnect electrical wire from Engine Coolant Level (ECL) Warning Switch -F66- and set aside coolant reservoir with coolant hoses -1- and -3- connected.







- Disconnect electrical 6-pin harness connector -1- at left from Heated Oxygen Sensor (HO2S) 2 -G108- (before catalytic converter) and Oxygen Sensor (O2S) 2 Heater 2 -Z28- (bank 2, sensor 1).

Checking internal resistance







- Connect multimeter between terminal 3 and 4 for resistance measurement.
- Specified value at room temperature: 2.5 to 10 ohm

If specified value is not obtained:
- Replace respective oxygen sensor before catalytic converter

If specified value is obtained:

Checking voltage supply







- Connect multimeter between terminal 3 and 4 for voltage measurement.
- Operate starter briefly.
- Specified value: approx. battery voltage
- Switch ignition off.

If there is no voltage:
- Connect multimeter for voltage measurement as follows:

Harness connector Terminal Measure to
3 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 3 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 Terminal Measure to
4 B+

- Operate starter briefly (engine can also start).
- 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 and Component Test







- Check the following wire connections for open circuit according to wiring diagram:
- Oxygen Sensor (O2S) Heater -Z19- (bank 1, sensor 1).

Harness connector Terminal Measure to
4 5

- Oxygen Sensor (O2S) Heater 2 -Z28- (bank 2, sensor 1).

Harness connector Terminal Measure to
4 4

Specified value: Wire resistance max 1.5 Ohms

- Check wires for short circuit to B+ or Ground (GND).
- Specified value:Infinite Ohms (no continuity)
- If necessary, repair wire connection.

If no malfunctions are detected:
- Replace Engine Control Module (ECM).

Assembly is performed in the reverse order of removal, note the following:

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". Mode 3: Check DTC Memory
2. If necessary, erase DTC memory see "Mode 4: Reset/erase diagnostic data". Mode 4: Reset/Erase Diagnostic Data
3. Generate readiness code. Readiness Code, Generating

- End diagnosis and switch ignition off.