Oxygen Sensor O2S Behind Three Way Catalytic Converter, Checking

Observe all safety precautions: SAFETY PRECAUTIONS 

View clean working conditions: CLEAN WORKING CONDITIONS 

For wiring diagrams, component locations, and connector views, Refer to the applicable SYSTEM WIRING diagram.

Special Tools And Workshop Equipment Required 

• Generic scan tool
• Multimeter
• Wiring diagram

Test Requirements 

• The Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- fuse Ok.
• Oxygen Sensor O2S Behind Three Way Catalytic Converter Heater - Z29- OK.
• Battery voltage at least 12.5 volts.
• All electrical consumers such as, lights and rear window defroster, switched off.
• Vehicles with automatic transmission, selector lever in position "P" or "N".
• A/C switched off.
• Ground (GND) connections between engine/transmission/chassis OK.
• Exhaust system between catalytic converter and cylinder head properly sealed.
• Coolant Temperature at least 80° C.

Test Procedure 

-- Perform a preliminary check to verify the customers complaint. Refer to PRELIMINARY CHECK 

Start Diagnosis 

-- Connect scan tool.

-- Start the engine and let it run at idle.

-- Select "Diagnostic mode 6: Check test results of components that are not continuously monitored".

-- Select "Test-ID 02: Oxygen sensor monitoring behind catalytic converter".

-- Select following Test-IDs.

-- Check the specified values at idle.

Test-ID			Specified value
			min.	max.
1	Rich to lean sensor barrier voltage		---	0.6241 V
2	Lean to rich sensor barrier voltage		---	0.6241 V
7	Minimum voltage at sensor for test cycle		---	0.450 V
8	Maximum voltage at sensor for test cycle		0.450 V	---
129	Sensor voltage lean		0	0.6241 V
130	Sensor voltage rich		0.6241 V	1.2998 V
131	Deceleration test		0 V	0.1599 V

If the specified values are obtained:

-- End diagnosis and switch ignition off.

If the specified values are not obtained:

-- Remove the right vehicle floor cover -arrows-. Refer to the appropriate service information.

Checking primary voltage

-- Disconnect the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- electrical harness connector -arrow-.

-- Switch the ignition on.

-- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- electrical harness connector terminals 3 to 4 for voltage.

Specified Value: 0.400 To 0.500 Volts 

-- Switch the ignition off.

If the specified value was not obtained:

-- Replace the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) - G130-. Refer to the appropriate service information.

If the specified value was obtained:

Checking Wiring

If the manufacturers test box is being used, perform the following step.

-- Install the test box.

If the manufacturers test box is not being used, perform the following step.

-- Remove the Motronic Engine Control Module (ECM) -J623-. Refer to the appropriate service information.

-- Using a multimeter, check the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) - G130- electrical harness connector terminals to the Motronic Engine Control Module (ECM) -J623- electrical harness connector T94 terminals for an open circuit according to the wiring diagram.

Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- Electrical Harness Connector Terminals	Motronic Engine Control Module (ECM) -J623- Electrical Connector T94 Terminals Or Test Box Sockets
3	34
4	62

Specified Value: 1.5 Ω Max. 

If the specification was not obtained:

-- Check the wiring for a short circuit to Battery (+), or an open circuit.

-- Check the electrical harness connector for damage, corrosion, loose or broken terminals.

-- If necessary, repair the faulty wiring connection.

If no malfunction is found in the wiring:

-- Replace the Motronic Engine Control Module (ECM) -J623-. Refer to the appropriate service information.

-- Install the right vehicle floor cover -arrows-. Refer to the appropriate service information.

Final Procedures 

After the repair work, the following work steps must be performed in the following sequence:

1. Check the DTC memory. Refer to DIAGNOSTIC MODE 03 - READ DTC MEMORY .
2. If necessary, erase the DTC memory. Refer to DIAGNOSTIC MODE 04 - ERASE DTC MEMORY .
3. If the DTC memory was erased, generate readiness code. Refer to READINESS CODE .