Test Chart 2
Oxygen Sensors And Oxygen Sensor Control Before Catalytic Converter, Checking
Recommended special tools and equipment
- VAG1526A multimeter
- VAG1594A connector test kit
- VAG1598/31 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.
- Vehicles with automatic transmission: Selector lever 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; "PID 05: Coolant temperature". Diagnostic Mode 01 - Read Current System Data
Work procedure
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.
- When servicing terminals in harness connector of oxygen sensor, use only gold-plated terminals.
- Connect diagnostic tester. VAS 5051, Connecting and Select Functions
- Start engine and let run at idle.
- In diagnostic function "33 - OBD", select "Mode 5: Check output of oxygen sensor signals".
- Select desired output of oxygen sensor signals according to the following table.
- Check values of output for oxygen sensor signals.
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:
- Test oxygen sensor heater before catalytic converter.
- Check intake system for leaks (false air).
- Check Oxygen Sensor (O2S) and oxygen sensor control behind Three Way Catalytic Converter (TWC). Oxygen Sensor and Oxygen Sensor Control Behind Catalytic Converter, Checking
- Check fuel pressure regulator and residual pressure.
- Check fuel injectors. Fuel Injectors, Checking
- Check Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80-. Testing and Inspection
- Check Fuel Pump (FP).
- Check exhaust system for proper seal. Testing and Inspection
- Check Secondary Air Injection (AIR) system for proper seal. Testing and Inspection
- Check vacuum lines for leaks.
- Connect test box at wiring harness to Engine Control Module (ECM), do not connect ECM.
Check oxygen sensor wires for Heated Oxygen Sensor (HO2S) -G39- (bank 1, sensor 1)
- Disconnect electrical 6-pin harness connector -1- from Heated Oxygen Sensor (HO2S) - G39- (before catalytic converter) and Oxygen Sensor (O2S) Heater -Z19- (bank 1, sensor 1).
- Check the following wire connections for open circuit according to wiring diagram:
Harness connector Terminal Test box Socket
1 70
2 71
5 51
6 52
- 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: Infinity ohm (no continuity)
- If necessary, repair wire connection.
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).
Check oxygen sensor wires for Heated Oxygen Sensor (HO2S) 2 -G108- (bank 2, sensor 1)
- Disconnect electrical 6-pin harness connector -4- from Heated Oxygen Sensor (HO2S) - G108- (before catalytic converter) and Oxygen Sensor (O2S) 2 Heater 2 -Z28- (bank 2, sensor 1).
NOTE: To reach the harness connectors, the left cover in engine compartment must be removed, the line to Engine Coolant Level (ECL) Warning Switch at bottom on reservoir must be disconnected, bolt (arrow) of coolant reservoir must be unscrewed and set it aside. Coolant hoses -1- to -3- remain connected.
- Check the following wire connections for open circuit.
Harness connector Terminal Test box Socket
1 13
2 14
5 12
6 15
- 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: Infinity ohm (no continuity)
- If necessary, repair wire connection.
If no malfunctions are found in wires:
- Replace Engine Control Module (ECM).
Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1. Check DTC memory. Diagnostic Mode 03 - Read DTC Memory
2. If necessary, erase DTC memory. Diagnostic Mode 04 - Erase DTC Memory
3. If DTC memory was erased, generate readiness code.
- End diagnosis and switch ignition off.