Volkswagen Workshop Service and Repair Manuals

Special tools, workshop equipment, testers, measuring instruments and auxiliary items required

• ◆ Fault reader V.A.G 1551 or vehicle system tester V.A.G 1552 with cable V.A.G 1551/3A

Test conditions

• ● → Fuse No. 1 must be OK.
• ● Vehicle stationary
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● If the vehicle is equipped with an air conditioning system, this must be switched off.
• ● Exhaust system between catalyst and cylinder head must be free of leaks
• ● Coolant temperature must be at least 80 °C, =>display group 04, display zone 3.
• ● Intake air temperature less than 60°C
  =>display group 04, display zone 4

Work sequence

• ‒ Connect the fault reader V.A.G 1551 (V.A.G 1552). Then switch ignition on and select engine control unit with the "Address word" 01.
  (Connecting fault reader and selecting engine control unit .)

Work step 1: Interrogate fault memory

• ‒ Press keys 0 and 2 for function "Interrogate fault memory" and confirm entry with Q key.

If a fault is stored:

• ‒ Rectify faults printed out using fault table:
  SAE P0 codes=> Page 01-34

If no fault is stored:

• ‒ Press ⇒key.

Work step 2: Erase fault memory

• ‒ Press keys 0 and 5 for the function "Erase fault memory" and confirm entry with Q key.

Note:

The readiness code is reset or erased each time fault memory is erased.

Note:

If the ignition is switched off between "Interrogate fault memory" and "Erase fault memory" the fault memory will not be erased.

• ‒ Press ⇒key.

Work step 3: Matching the throttle valve control part to the engine control unit

• ‒ Press keys 0 and 4 for the function "Initiating basic settings" and confirm entry with Q key.

• ‒ Press keys 0, 6 and 0 for the "Display group number 60" and confirm entry with Q key.

• ‒ Check specifications in display zones 3 and 4:
       Display zone 3: 0...9
       Display zone 4: ADP. runs, ADP. OK

• ‒ Terminate engine basic setting at earliest after 30 seconds by pressing the⇒ key.

If the display does not indicate as described:

• ‒ Check throttle valve control part
  => Page 24-46 .

If the display indicates as described:

• ‒ Start engine and run at idling speed.

Work step 4: Activated charcoal filter system diagnosis (tank breathing system)

Note:

• ◆ During the work sequence the engine must not be switched off.

• ‒ Press keys 0 and 4 for the "Introduce basic setting" function and confirm entry with Q key.

• ‒ Press keys 0, 7 and 0 for "Display group number 70" and confirm entry with Q key.

Note:

The engine must not be loaded during this diagnosis because the diagnosis will be interrupted and will not be started again until the engine is revved-up.

When the diagnosis is initiated by the engine control unit the display in display zone 4 jumps from "Test OFF" to "Test ON"

• ‒ Run engine at idling speed until the
       specification "TVV OK"
  is displayed in display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-18 .

If the display indicates as described:

• ‒ Press C key.

Work step 5: Lambda regulation system diagnosis

• ‒ Press keys 0, 3 and 7 for "Display group number 37" and confirm entry with Q key.

• ‒ Depress brake pedal.

• The engine speed is increased by the control unit to
       approx. 1100...1300 rpm.

• ‒ Allow the engine to continue running at increased idling speed until the
       specification "Syst. OK."
  is displayed in display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-18 .

If the display indicates as described:

• ‒ Press ⇒key.

• The engine speed decreases to idling speed.

Work step 6: Lambda probe ageing diagnosis

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

• ‒ Press keys 0, 3 and 0 for the "Display group number 30" and confirm entry with Q key.

• ‒ Check Lambda control status before catalyst (display zone 1):
       Specification: 1 1 1
  (Significance => Page 01-111 )
• ‒ Check Lambda control status after catalyst (display zone 2):
       Specification: 1 1 1
  (Significance => Page 01-111 )

Notes:

• ◆ The first position of the 3 digit number block fluctuates between 0 and 1 (Lambda probe heating on and off).
• ◆ Depending upon the status of the Lambda control the 3 digit number block can show 0 or 1.
• ◆ The bits in display zones 1 and 2 will not be set to 1 until the catalyst temperature has risen to above 400.0 °C (=> display group 34, display zone 2).

If the specifications are not obtained:

• ‒ Interrogate fault memory => Page 01-18 .

If the specifications are obtained:

• ‒ Press ⇒key.

• ‒ Press keys 0 and 4 for the "Introduce basic setting" function and confirm entry with Q key.

• ‒ Press keys 0, 3 and 4 for "Display group number 34" and confirm entry with Q key.

• ‒ Depress brake pedal.

• The engine speed is increased by the control unit to
       approx. 1100...1300 rpm.

• ‒ Maintain the engine speed until the display
       in display zone 4 jumps from "Test OFF" to "Test ON". The catalyst temperature in
       display zone 2 must be min. 400 °C.

Note:

This process can take a few minutes.

• ‒ Check amplitude duration in display zone 3:
       Specification: 0.7... 2.00
• ‒ Continue to maintain engine speed until the specification "B1-P1" appears in
       display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-18 .

If the display indicates as described:

• ‒ Press C key.

• The engine speed decreases to idling speed.

• ‒ Press keys 0, 3 and 6 for "Display group number 36" and confirm entry with Q key.

• ‒ Depress brake pedal.

• The engine speed is increased by the control unit to
       approx. 1100...1300 rpm.

• ‒ Maintain the engine speed until the display
       in display zone 4 jumps from "Test OFF" to "Test ON". The catalyst temperature in
       display zone 2 must be min. 400 °C.

Note:

This process can take a few minutes.

• ‒ Check amplitude duration in display zone 3:
       Specification: 0.7... 2.00
• ‒ Continue to maintain engine speed until the specification "B1-P2 OK" appears in
       display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-18 .

If the display indicates as described:

• ‒ Press C key.

• The engine speed decreases to idling speed.

Work step 7: Catalyst diagnosis

Note:

The diagnosis will only be terminated if the Lambda probe ageing diagnosis is first successfully completed.

• ‒ Press keys 0, 4 and 6 for "Display group number 46" and confirm entry with Q key.

• ‒ Depress brake pedal.

• The engine speed is increased by the engine control unit to
       approx. 1100...1300 rpm.

• ‒ Maintain the engine speed until the display
       in display zone 4 jumps from "Test OFF" to "Test ON". The catalyst temperature in
       display zone 2 must be min. 400 °C.

• ‒ Check the amplitude ratio in display zone 3:
       Specification: max. 0.50
• ‒ Continue to maintain the speed until the specification "Cat B1 OK" appears in
       display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-18 .

If the display indicates as described:

• ‒ Press ⇒key.

• The engine speed decreases to idling speed.

Work step 8: Exhaust gas recirculation diagnosis

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

• ‒ Press keys 0, 7 and 5 for the "Display group number 75" and confirm entry with Q key.

• ‒ Drive a short distance (about 3 ... 4 min).

• The engine speed must be raised to
       about 1800 ... 3600 rpm
  and the coolant temperature must be
       >70 °C .

• ‒ Take foot quickly from accelerator pedal to simulate over-run.

• The display in display zone 4 jumps
       from"Test OFF" to "Test ON".
• The over-run period must be about 8 seconds.

• ‒ Check that display zone 4 shows the specification
       "Syst. OK".

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-18 .

If the display indicates as described:

• ‒ Press ⇒key.
• ‒ Read readiness code=> Page 01-63