Sensor and Sensor Control Check
Heated Oxygen Sensor (HO2S) And Oxygen Sensor (O2S) Control Before Catalytic Converter, Checking
Special tools and equipment
- VAG 1526A
- VAG 1594A
- VAG 1598/31
- VAS5051 with VAS5051/1
Test requirements:
- No leaks in exhaust system
- Coolant temperature at least 80 degree C, see display group 004, display zone 3.
Test sequence
- Connect vehicle diagnostic, testing and information system VAS5051 and select vehicle system "01 -Engine electronics". Engine must be running at idling speed. Connecting VAS 5051 Scan Tool
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 "heated oxygen sensor (HO2S) status" indicates the condition of the oxygen sensor (O2S) control and the heated oxygen sensors (HO2S).
Display Group 030:
Significance of 3-digit readout of display group 030
NOTE: The first digit of the 3-digit display (heating) fluctuates between 0 and 1.
Display on VAS5051:
Only continue with the test if the displays have reached "111" in display zones -1- and -3- at least once.
- Press <- button.
Checking heated oxygen sensor (HO2S) learned values and oxygen sensor (O2S) 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 oxygen sensor learned values in display zones -1 to 4-.
Display Group 032:
- Press <- 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-.
Display Group 033:
- Exit function "04 - Basic setting" by pressing <- button.
Continuation
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 test drive to free heated oxygen sensors (HO2S) 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 heated oxygen sensor (HO2S) before catalytic converter.
- Check heated oxygen sensor (HO2S) before catalytic converter for aging.
Evaluating display group 032
Display Zone 1/3 Or 2/4 - Part 1:
Display Zone 1/3 Or 2/4 - Part 2:
Evaluating display group 033
Display Zone 2/4:
Checking basic voltage
Test requirements:
- Fuse for heated oxygen sensor (HO2S) OK.
- Disconnect 6-pin connector of relevant heated oxygen sensor before catalytic converter.
- 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 heated oxygen sensor (HO2S) lines Bank 1 or Bank 2.
If specified value is obtained:
- Replace relevant heated oxygen sensor (HO2S) before catalytic converter.
Check heated oxygen sensor (HO2S) wiring, bank 1, heated oxygen sensor (HO2S) -G39- before catalytic converter
- Disconnect 6-pin connector of bank 1, heated oxygen sensor (HO2S) -G39- before catalytic converter.
- Connect test box VAG 1598/31 to wiring harness for engine control module; engine control module must not be connected. Wiring and Component Testing Using VAG1598/31 Test Box
- Test for open circuit in following wiring connections.
Connector Test box VAG 1598/31
terminal Socket
1 70
2 71
5 51
6 52
- Repair open circuit, if necessary.
- Check for shorts between two lines.
If no wiring malfunction is detected:
- Replace engine control module.
Check heated oxygen sensor (HO2S) wiring, bank 2, Heated Oxygen Sensor (HO2S) 2 -G108- before catalytic converter
- Disconnect 6-pin connector of bank 2, Heated Oxygen Sensor (HO2S) 2 -G108- before catalytic converter.
- Connect test box VAG 1598/31 to wiring harness for engine control module; engine control module must not be connected. Wiring and Component Testing Using VAG1598/31 Test Box
- Test for open circuit in the following wiring connections.
Connector Test box VAG 1598/31
terminal Socket
1 13
2 14
5 12
6 15
- Repair open circuit, if necessary.
- Check for shorts between two lines.
If no wiring malfunction is detected:
- Replace engine control module.