With Manufacturer Scan Tool
Oxygen Sensor And Sensor Control Before Catalyst, Checking
NOTE:
- Raise vehicle to reach oxygen sensor connector
- The oxygen sensor (before catalyst) has constant regulation and can be distinguished by a 6-pin connector from the oxygen sensor after catalyst.
- Only gold-plated terminals must be used to repair the terminals in the oxygen sensors connectors.
Special tools and equipment
- Scan tool VAG 1551 or vehicle system tester V.A.G 1552 with cable VAG 1551/3B
- Test box VAG 1598/31
- Hand multimeter V.A.G 1526 or multimeter V.A.G 1715
- Adapter set V.A.G 1594
- Wiring diagram
Check conditions
- All fuses must be OK
- The battery voltage must be at least 11.5 V
- Exhaust system between catalyst and cylinder head must be free of leaks
- Coolant temperature must be at least 85 °C See display group 04, display zone 3
Functional check
- Connect scan tool VAG 1551 (V.A.G 1552) Start engine and select "Address word" 01 of engine control module. Engine must be running at idle speed.
Connecting scan tool and selecting Engine Control Module (ECM). Refer to "Scan Tool Testing/Scan Tool Connecting and Initial Checks/VAG1551 Scan Tool" Testing and Inspection
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons 0 and 8 for function "Read Measuring Value Block" and confirm entry with Q button.
Indicated on display
Read Measuring Value Block
Input display group number XXX
- Press buttons 0, 3 and 0 for "Display group number 30" and confirm entry with Q button.
Indicated on display (1-2 = Display zones)
Read Measuring Value Block 30 ->
1 2
- Check status of the oxygen sensor control before catalyst (display zone 1):
Specification: 111
Significance of 3 digit number block in display zone 1
NOTE: The first position of the 3 digit number block fluctuates between 0 and 1 (Heated oxygen sensor on and off).
If the specification is not obtained:
- Check Heated oxygen sensor before catalyst.
If the specification is obtained:
- Change to display group 32 as follows:
- Press C button.
- Press buttons 0, 3 and 2 for "Display group number 32" and confirm entry with Q button.
Indicated on display: (1 to 2 = Display zones)
Read measured value block 32 ->
1 2
- Check oxygen sensor control learned value at idling (additive) in display zone 1.
Specification: -10.0 to 10.0 %
- Check oxygen sensor control learned value at part load (multiplicative) in display zone 2.
Specification: -10.0 to 10.0 %
If the specification is not obtained:
- Evaluating display group 32 Refer to "Scan Tool Testing/Measuring Value Blocks/Evaluating Measured Value Blocks/Display Groups 30 to 49, 107 (Oxygen Sensor Control)" Testing and Inspection
If the specification is obtained:
- Change to display group 33 as follows:
VAG 1551: Press button 3
V.A.G 1552: Press button Uparrow
Indicated on display (1-2 = Display zones)
Read Measuring Value Block 33 ->
1 2
- Observe oxygen sensor control in display zone 1. Display must fluctuate at least 2 % in range
-10.0 to 10.0%
If the oxygen sensor control in display zone 1 does not fluctuate as stated:
- Press -> button.
- Press buttons 0 and 6 for "End data transfer" function and confirm input with Q button.
- Switch ignition off.
- Carry out a test drive to remove possible residue on oxygen sensor and repeat check.
Observe the valid safety precaution carrying out a road test.
If the specifications in display zone 1 are not obtained even after a test drive, or the value does not fluctuate by at least 2 %:
- Replace oxygen sensor before catalyst (G39).
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory. Refer to "Displaying and Reading Trouble Codes/With Manufacturers Scan Tool/DTC Memory Checking and Erasing" Testing and Inspection
Checking oxygen sensor wiring for oxygen sensor 1
- Remove inner plenum chamber cover, left:
- Connect test box V.A.G 1598/31 to control module wiring harness. The engine control module is not connected by this action.
- Remove protective cover -arrows and separate 6-pin connector (black) - 1- to oxygen sensor before catalyst (G39).
- Check wiring for open circuit between test box and 6-pin connector (to control module) according to wiring diagram.
- Terminal 1 + socket 70
- Terminal 2 + socket 71
- Terminal 5 + socket 51
- Terminal 6 + socket 52
Wire resistance: Max. 1.5 Ohms
- Additionally check wires all for short to one another.
Specification: Infinity Ohms
If no wiring problem is detected:
- Replace oxygen sensor before catalyst (G39).
- Check DTC memory, if necessary, repair any malfunctions and then erase DTC memory. Refer to "Displaying and Reading Trouble Codes/With Manufacturers Scan Tool/DTC Memory Checking and Erasing" Testing and Inspection
- Read readiness code. If DTC memory has been erased or engine control module was disconnected from permanent positive, readiness code must be generated again.
Refer to "Monitors, Trips and/or Drive Cycle/Readiness Code, Displaying" Testing and Inspection
Refer to "Monitors, Trips and/or Drive Cycle/Readiness Code, Generating" Testing and Inspection