With Manufacturer's Scan Tool
Knock Sensors, Checking
NOTE:
- It is extremely important to keep to the tightening torque of 20 Nm (15 ft lb) to ensure the knock sensors function normally.
- Only gold plated terminals may be used when servicing the knock sensor harness connector terminals.
Special tools and equipment
- VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool with VAG1551/3 adapter cable
- VAG1598/31 test box
- Multimeter (Fluke 83 or equivalent)
- VW1594 adapter set
- Wiring diagram
Test conditions
- The On Board Diagnostic (OBD) must have recognized a malfunction of one or both knock sensors.
- Coolant temperature must be at least 85 °C See display group 28, display field 3.
Checking function
- Connect VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool. Start engine and press buttons -0- and -1- to select "Engine Electronics" address word 01 (when doing this engine must be running at idle speed).
Indicated on display:
Rapid data transfer HELP
Select function XX
Press buttons -0- and -8- to select "Read Measuring Value Block" function 08, and press -Q- button to confirm input.
Indicated on display:
Read Measuring Value Block
Input display group number XXX
- Press buttons -0-, -2- and -8- to input display group number 28 (028), and press -Q- button to confirm input.
Indicated on display: (1-4 = display fields)
Read Measuring Value Block 28 ->
1 2 3 4
NOTE: Checking the knock sensors must be performed during a road test because the diagnostic of the knock sensors is not activated until the engine speed exceeds 2000 rpm and the engine is under more than a 40% load.
- Carry out road test and check knock control Specified values on display (display fields 3 and 4).
Observe the valid safety precautions when carrying out a road test. Refer to "Ignition System/Service Precautions", Technician Safety Information
Display Group 028: Ignition, Knock Sensor:
If the specification is obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.
Continuation
If the specifications are not obtained:
- Press -> button.
- Press buttons -0- and -6- to select "End Output" function 06 and press -Q- button to confirm input.
- Switch ignition off.
Knock Sensor (KS) 1 -G61-
- Disconnect white 3-pin harness connector to knock sensor 1 (arrow).
Knock Sensor (KS) 2 -G66-
- Disconnect brown 3-pin harness connector to knock sensor 2 (arrow).
- Measure resistance between knock sensor terminals -1- + -2-, -1- + -3- and
Specified value: infinity ohms
- Remove wiper arms and plenum chamber cover.
If the specification is not obtained:
- Replace Knock Sensor (KS) 1 -G61- or replace Knock Sensor (KS) 2 -G66-. Refer to item 15 or item 11 under "Ignition System", Service and Repair
- Check DTC memory. If necessary, repair any malfunctions and erase DTC memory.
- Display readiness code.
If the DTC memory has been erased or the ECM was disconnected from permanent battery (B+) voltage, the readiness code must be generated again.
If the specification is obtained:
- Check wiring.
Checking wiring
- Remove wiper arms and plenum chamber cover.
- Connect VAG1598/31 test box to control module wiring harness. Engine Control Module (ECM) is not connected by this action.
- Check wiring between test box and 3-pin harness connector for open circuit using wiring diagram.
-G61-: -G66-:
Terminal -1- + socket 106 107
Terminal -2- + socket 99 99
Terminal -3- + socket 108 108
Wire resistance: max. 1.5 ohms
- Also, check wires for short to one another.
Specified value: infinity ohms
If no wiring fault is detected:
- Loosen knock sensor and re-tighten to 20 Nm (15 ft lb).
- Perform road test again and check knock control specifications on display.
During the road test the following conditions must be fulfilled:
- Coolant temperature must exceed 85 °C.
- When temperature is reached, operating conditions Idling, Part throttle, Wide Open Throttle (WOT), and Overrun must be attained several times
- At Wide Open Throttle (WOT) engine speed must exceed 3500 RPM
- Again, check DTC memory of control module.
If the malfunction is still present:
- Replace knock sensor/s -G61- or -G66- Refer to item 15 or item 11 under "Ignition System", Service and Repair
- Check DTC memory. If necessary, repair any malfunctions and erase DTC memory.
- Display readiness code.
If DTC memory has been erased, or Engine Control Module (ECM) was disconnected from permanent battery (B+) voltage, readiness code must be generated again.