Oxygen Sensor And Regulation After 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 Ok.
  Fig 1: Fuses On E-Box In Engine Compartment, Left Side

  Courtesy of AUDI OF AMERICA, LLC
• Oxygen Sensor (O2S) 1 (behind Three Way Catalytic Converter (TWC)) Heater - Z29- OK. Refer to OXYGEN SENSOR 1 HEATER, CHECKING .
• 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-.

Checking primary voltage 

-- Disconnect the brown 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-. Refer to Repair information.

If the specified value was not obtained:

Checking wiring 

If the manufacturers test box is being used. Perform the following step.

-- Install the test box. Refer to Repair information.

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

-- Remove the Motronic Engine Control Module (ECM) -J220-. Refer to Repair 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) -J220- electrical harness connector T94 terminals for an open circuit according to the wiring diagram.

Terminal	Test box socket
3	76
4	77

Specified value: 1.5 Ω Max.

If the specification was not obtained:

-- Check the wiring for a short circuit to each other, Battery (+), and Ground (GND).

-- Check the electrical harness connector for damage, corrosion, lose 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) -J220-. Refer to Repair information.

-- 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 .