With Manufacturer's Scan Tool
Oxygen Sensor (O2S) And Oxygen Sensor Control Before Three Way
Catalytic Converter (TWC), Checking
NOTE: The Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC) (Bank 1, sensor 1) changes to Oxygen Sensor 1. If this Oxygen Sensor (O2S) is damaged, e.g. through contamination or overheating, the control value can be changed. Deviations from Oxygen Sensor 1 are recorded by the Oxygen Sensor (O2S) after the Three Way Catalytic Converter (TWC) (Bank 1, sensor 2). If these deviations are recognized downward or upward it influences the control before the Three Way Catalytic Converter (TWC) in such a way that it is generally raised or lowered accordingly.
Special tools and equipment
- V.A.G 1526 A Multimeter
- V.A.G 1594 A Connector test kit
- V.A.G 1598/31 Test box
- VAS 1788/10
- VAS 5051 with 5051/1
Test requirements:
- No leaks in exhaust system
- Coolant temperature at least 80 degree C.
Test sequence
- Connect vehicle diagnostic, testing and information system VAS 5051 and select vehicle system "01 -Engine electronics" in selection. Engine must be run at idle. Connecting VAS 5051/VAG 1551 Scan Tool (ST)
Display on VAS 5051:
- Under -1- select diagnostic function "04 - Basic setting".
Display on VAS 5051:
1 Enter display group
- Enter "030" for "display group number 030" in field -2- and confirm entry by pressing -Q- button.
Display on VAS 5051:
- Check indication in display group -2-.
NOTE:
- By increasing the engine speed the specified values are obtained more quickly.
- The "Oxygen Sensor status" indicates the condition of the Oxygen Sensor control and the Oxygen Sensor (O2S).
Display Group 030:
Display on VAS 5051:
- Only continue test if display in display field -2- has reached "110" at least once.
- Press <- button.
Oxygen Sensor control after Three Way Catalytic Converter (TWC), checking
- Set engine speed with VAG 1788/10 RPM adjuster to 2000 rpm.
- Press <- button.
Display on VAS 5051:
1 Enter display group
- Enter "037" for "display group number 037" in field -2- and confirm entry by pressing -Q- button.
Display on VAS 5051:
- Check Oxygen Sensor (O2S) voltage in display field -2-.
- Check Oxygen Sensor (O2S) correction value in display field-3- and diagnosis result in display field -4-.
Display Group 037:
Continued
If specification in display field 3 or 4 is not obtained:
- Perform test drive to free Oxygen Sensor (O2S) from any possible residues and repeat test.
If specified value in display field 3 or 4 is not obtained, even after a test drive has been performed:
- Replace Oxygen Sensor (O2S) before Three Way Catalytic Converter (TWC).
NOTE: If the Oxygen Sensor (O2S) voltage is OK and after a road test the Oxygen Sensor correction value is still outside the specification, this indicates aging of the Oxygen Sensor before the Three Way Catalytic Converter (TWC).
Checking basic voltage
- Unscrew the protective cover -2- (arrow)
- Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) Behind Three Way Catalytic Converter (TWC) -G130-.
- Connect multimeter between terminals 3 and 4 to measure voltage.
- Switch ignition on.
- Specified value: 0.400...0.500 V
- Switch ignition off.
If specified value is not obtained:
- Check oxygen sensor wiring harness.
If specified value is obtained:
- Replace Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC) -G130-.
Oxygen sensor wiring harness, checking
- Disconnect 4-pin connector -2- (brown) to Oxygen Sensor (O2S) after Three Way Catalytic Converter (TWC) -G130-.
- Connect test box V.A.G 1598/31 to wiring harness for engine control module; do not connect directly to Engine Control Module (ECM). Electrical Testing Using VAG1598/31 Test Box
- Check for open circuit in following wiring connections:
Connector Test box V.A.G 1598/31
terminal Socket
3 68
4 69
- Repair open circuit, if necessary.
- Check for shorts between two wires.
If wiring is OK:
- Replace Engine Control Module (ECM).