Jetta GLS VR6 V6-2.8L (AFP) (2001)
Knock Sensor: Testing and Inspection
With Manufacturer's Scan Tool
Knock Sensors, Checking
NOTE:
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It is extremely important to keep to the tightening torque of 20 Nm (15 ft lb) to ensure the knock sensors function normally.
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Only gold plated terminals may be used when servicing the knock sensor harness connector terminals.
Special tools and equipment
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VAG1551 Scan Tool (ST) or VAG1552 mobile scan tool with VAG1551/3 adapter cable
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VAG1598/31 test box
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Multimeter (Fluke 83 or equivalent)
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VW1594 adapter set
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Wiring diagram
Test conditions
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The On Board Diagnostic (OBD) must have recognized a malfunction of one or both knock sensors.
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Coolant temperature must be at least 85 °C See display group 28, display field 3.
Checking function
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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
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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.
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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", See: Powertrain
Management/Ignition System/Service Precautions/Technician Safety Information