Check Oxygen Sensor and Oxygen Sensor Control Behind Catalytic Converter

Check Oxygen Sensor And Oxygen Sensor Control Behind Catalytic Converter.

NOTE: The oxygen sensor before catalytic converter (bank 1, sensor 1 or bank 2, sensor 1) regulates to Lambda 1. If this oxygen sensor is damaged, e.g. due to soiling or overheating, the regulation value may have shifted. Deviations from Lambda 1 are detected by the oxygen sensor behind catalytic converter (bank 1, sensor 2 or bank 2, sensor 2). If it recognizes the deviations downward or upward, it influences the regulation before catalytic converter, generally increasing or decreasing it respectively.







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:
- Fuses for engine electronics OK
- Ground (GND) connections at engine and transmission OK
- Oxygen sensor heater OK; check.
- Exhaust system free of leaks.
- Parking brake engaged.
- Selector lever of automatic transmission in position "P" or "N".
- Electrical consumers switched off (radiator fan must NOT run during test).
- A/C switched off.
- Coolant temperature at least 80 degrees C see "Mode 1: Check measuring values "; "PID 05: Coolant temperature". Mode 1: Check Measured Values

Procedure
- Connect diagnostic tester.
- Start engine and let run at idle.
- In diagnostic function "33 - OBD", select "Mode 5: Check output of oxygen sensor signals".

NOTE:
- Bank 1 = cylinder bank 1 in direction of travel, right; Bank 2 = cylinder bank 2 in direction of travel, left.
- When selecting the diagnostic mode, the entry is always performed in "Bank 1 sensor 1".
- If the Vehicle Diagnostic, Testing and Information System VAS 5051 or the Vehicle Diagnostic and Information System VAS 5052 is used for checking the lambda test results, the respective oxygen sensor can be selected by pressing button 1, 2, 5 and 6.

- Button 1 = Bank 1 sensor 1,
- Button 2 = Bank 1 sensor 2,
- Button 5 = Bank 2 sensor 1,
- Button 6 = Bank 2 sensor 2.
- Select the desired output of oxygen sensor signals according to the following table.










- Check values of output for oxygen sensor signals.
*) V = Voltage in Volts (oxygen sensor signal)
**)t = Time in seconds

If specified values are not obtained:
- Road test vehicle in order to free oxygen sensors of possible residue and repeat test.

If specified values are not obtained again:

Checking primary voltage







- 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 (behind Three Way Catalytic Converter (TWC)) -Z29- (bank 1, sensor 2).







- 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 left electrical 4-pin harness connector -4- from Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- and Oxygen Sensor (O2S) Heater 2 (behind Three Way Catalytic Converter (TWC)) -Z30- (bank 2, sensor 2).








- Connect multimeter between terminal 3 and 4 for voltage measurement.
- Switch ignition on.
- Specified value: 0.400 to 0.500 V
- Switch ignition off.

If specified value is not obtained:
- Check oxygen sensor wires See Bank 1 and Bank 2.

If specified value is obtained:
- Replace respective oxygen sensor behind catalytic converter

Check oxygen sensor wires for Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- (bank 1, sensor 2)
- 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:

Harness connector Test box Socket
Terminal
3 68
4 69

Specified value: Wire resistance max 1.5 Ohms

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

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

Check oxygen sensor wires for Oxygen Sensor (O2S) 2 Behind Three Way Catalytic Converter (TWC) -G131- (bank 2, sensor 2)
- 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.

Harness connector Test box Socket
Terminal
3 10
4 11

Specified value: Wire resistance max 1.5 Ohms

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

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

Assembly is performed in 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