Oxygen Sensor Regulation Behind Catalytic Converter, Checking

Special tools and workshop equipment required 

• Multimeter.
• Wiring diagram.

Test requirements 

• The Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130- fuse 21 in Fuse Panel B is OK.
  Fig 1: Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of VOLKSWAGEN GROUP OF AMERICA, INC.
• Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater - G130- 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 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 "Monitor-ID 02: Oxygen sensor monitoring behind catalytic converter".

-- Select following Test-IDs.

-- Check the specified values at idle and compare the results to the min/max values given in the Mode 6 table.

If the specified values were obtained:

-- Switch ignition Off. Fault is not active at this time. Check for poor connections, loose terminals and harness check.

If the specified values were Not obtained:

-- Remove the right vehicle floor cover -arrows-.

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 obtained:

-- Replace the Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) - G130-.

If the specified value was Not obtained:

Checking wiring 

-- Remove the Motronic Engine Control Module (ECM) -J623-.

-- 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 chart below.

Heated Oxygen Sensor (HO2S) -G130- electrical harness connector terminal	Motronic Engine Control Module (ECM) -J623- electrical connector T94 terminal
3	33
4	84

Specified value: 1.5 Ω Max.

If the specified value was Not obtained:

-- Check the wiring for an open, high resistance or short to ground.

-- 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 and the voltage was NOT present:

-- Replace the Motronic Engine Control Module (ECM) -J623-.

-- Install the right vehicle floor cover -arrows-.

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 .