SEAT Workshop Service and Repair Manuals

Notes:

• ◆ It is extremely important to keep to the tightening torque of 20 Nm to ensure the knock sensors perform perfectly.
• ◆ The knock sensor might misinterpret vibrations of loose components as knocking noises. Therefore check that engine ancillaries are securely mounted.
• ◆ Only gold-plated contacts may be used when servicing the knock sensor connector contacts.

Check conditions

• ● Self-diagnosis has detected a fault in the knock sensor , Interrogating and erasing fault memory.
• ● The engine speed must be at least 2500 rpm =>display group 28, display zone 1
• ● The engine load musts be at least 40.0 % =>display group 28, display zone 2
• ● Coolant temperature must be at least 80 °C, =>display group 28, display zone 2.

Test sequence

• ‒ Connect fault reader V.A.G 1551 (V.A.G 1552). Start engine and select "Address word" 01 of engine control unit. When doing this the engine must be running at idling speed.
  (Connecting fault reader and selecting engine control unit => Page 01-9.)

• ‒ Press keys 0 and 8 for the function "Read measured value block" and confirm entry with Q key.

• ‒ Press keys 0, 2 and 8 for the "Display group number 28" and confirm entry with Q key.

Note:

Checking the knock sensors must be performed during a test drive because the diagnosis of the knock sensors is not activated until the engine speed exceeds 2500 rpm and the engine is loaded by more than 40 %.

• ‒ Carry out test drive with a 2nd person to observe display.

Observe the valid safety precautions when carrying out a test drive => Page 28-5.

• ‒ Check specification for knock control in display zone 4.
      Specification: Syst. OK

If the specification is obtained:

• ‒ Press ⇒key.
• ‒ Press keys 0 and 6 for the "End output" function and confirm input with the Q key.
• ‒ Switch off ignition.

If the specification is not obtained:

Checking resistances and wiring

• ‒ → Separate the 2-pin connector to knock sensor 1 (G61) -1- and/or 2-pin connector to knock sensor 2 (G66) -2-.

• ‒ → Measure resistance between the contacts 1+2 of knock sensors.
      Specification ∞ω

If the specification is not obtained:

• ‒ Replace knock sensor(s)

If the specification is obtained:

• ‒ Remove battery.
• ‒ → Connect test box V.A.G 1598/31 to control unit wiring harness. The engine control unit remains disconnected.

• ‒ → Check wiring for open circuit between test box and 2-pin connectors using current flow diagram.
          G61:    G66:
      Contact 1+socket    106    107
      Contact 2+socket     99     99
  Wire resistance: max. 1.5 ω
• ‒ Additionally check wires for short to one another.
      Specification: ∞ω

If no fault is detected in the wiring:

• ‒ Loosen knock sensor and tighten again to 20 Nm.
• ‒ Carry out test drive again.

• During the road test the following operating conditions must be fulfilled:
• ‒ The coolant temperature must exceed 80 °C .
• ‒ When the temperature is reached, the operating conditions
      Idling
      Part throttle
      Enrichment
      Full throttle
      Overrun
  must be attained several times.
• ‒ At full throttle the speed must exceed 3500 rpm.

• ‒ Again interrogate the control unit fault memory.

If the fault is still present:

• ‒ Replace knock sensor(s)