Oxygen Sensors and Oxygen Sensor Control Before Catalytic Converter, Checking
Oxygen Sensors And Oxygen Sensor Control Before Catalytic Converter, Checking
Special tools and equipment
- VAG1526 A
- VAG1594 A
- VAG1598/31
- VAS5051 with VAS5051/1
Test requirements
- No leaks in exhaust system
- Engine coolant temperature at least 80 degrees C, display group 004, display zone 3.
Test sequence
- Connect vehicle diagnostic, testing and information system VAS5051 and select vehicle system "01-Engine electronics" in selection. Engine must be running at idling speed.
Display on VAS5051:
- Under -1- select diagnostic function "04 - Basic setting".
Display on VAS5051:
1. Enter display group
- Enter "030" for "display group number 030" in zone -2- and confirm entry by pressing -Q- button.
Display on VAS5051:
- Check specifications in display zones -1- and -3-.
NOTE:
- By increasing the engine speed the specified values are achieved quickly.
- The "oxygen sensor status" indicates the condition of the oxygen sensor control and the oxygen sensors.
NOTE: The first digit of the 3-digit display (heating) fluctuates between 0 and 1.
Display on VAS5051:
- Only continue with test if displays have reached "111" in display zones -1- and -3- at least once.
- Press square button.
Checking oxygen sensor learned values and oxygen sensor control
Display on VAS5051:
1. Enter display group
- Enter "032" for "display group number 032" in zone -2- and confirm entry by pressing -Q- button.
- Check values in display zones -1- to -4-.
- Press square button.
Display on VAS5051:
1. Enter display group
- Enter "033" for "display group number 033" in zone -2- and confirm entry by pressing -Q- button.
Display on VAS5051:
- Activate basic setting by pressing -A- button.
- Check indication in display fields -1- to -4-.
Note on display zones 2 and 4:
Displayed is the oxygen sensor voltage signal which was prepared and smoothed in the engine control module. 1.5 V in the display corresponds to oxygen sensor 1 (with the engine at operating temperature without secondary air system influence).
- Exit function "04 - Basic setting" by pressing square button.
(cont.)
If specification is not obtained in display zone 1 or display zone 3, or if the value does not fluctuate by at least 2%:
- Perform drive test to free oxygen sensors from any possible residues and repeat test.
If the specified result is not achieved in display zones 1 or 3, or if the value does not fluctuate by at least 2%, even after the test drive:
- Check basic voltage.
- Check oxygen sensor heating before catalytic converter.
- Check oxygen sensor before catalytic converter for aging.
Evaluating display group 032
Evaluating display group 032
Evaluating display group 033
Checking basic voltage
Test requirements:
- Fuse for oxygen sensors OK.
- Disconnect 6-pin connector of relevant oxygen sensor before catalytic converter see Fig. 6 and see Fig. 7.
- Connect multimeter between terminals 1 and 5 to measure voltage.
- Switch ignition on.
Specified value: 0.400 to 0.500 V
- Switch ignition off.
If specified value is not obtained:
- Check oxygen sensor wiring:
Bank 1 or Bank 2
If specified value is obtained:
- Replace relevant oxygen sensor before catalytic converter.
Check oxygen sensor wiring, bank 1, sensor 1, Heated Oxygen Sensor (HO2S) -G39-
- Disconnect 6-pin connector of bank 1, Heated Oxygen Sensor (HO2S) -G39- see Fig. 6.
- Connect test box VAG1598/31 to wiring harness for engine control module; engine control module must not be connected. Wiring and Component Check With Test Box VAG 1598/31
- Test for open circuit in following wiring connections.
Connector Test box VAG1598/31
terminal Socket
1 70
2 71
5 51
6 52
- Repair open circuit, if necessary.
- Check for shorts between two wires.
If no wiring malfunction is detected:
- Replace engine control module.
Check oxygen sensor wiring, bank 2, sensor 1, Heated Oxygen Sensor (HO2S) 2 -G108-
- Disconnect 6-pin connector of bank 2, Heated Oxygen Sensor (HO2S) 2 -G108- see Fig. 7.
- Connect test box VAG1598/31 to wiring harness for engine control module; engine control module must not be connected. Wiring and Component Check With Test Box VAG 1598/31
- Test for open circuit in following wiring connections.
Connector Test box VAG1598/31
terminal Socket
1 13
2 14
5 12
6 15
- Repair open circuit, if necessary.
- Check for shorts between two wires.
If no wiring malfunction is detected:
- Replace engine control module.