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 1551/3

Test conditions

• ● → All fuses must be OK.
• ● Vehicle stationary
• ● On vehicles with automatic gearbox selector lever in "P" or "N" position
• ● All electrical consumers, e.g. lights and rear window heating must be switched off.
• ● Intake air temperature less than 60°C
  =>display group 04, display zone 4
• ● Coolant temperature must be at least 80 °C, =>display group 04, display zone 3.

Work 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 .)

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 01-37

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.

Note:

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

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...8
       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 24-42 .

If the display indicates as described:

• ‒ Start engine and run at idling speed.

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

• ‒ 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 01-20 .

If the display indicates as described:

• ‒ Press C key.

Work step 5: Lambda probe ageing diagnosis for Lambda probe before catalyst

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

• ‒ Depress brake pedal and hold it down.

• Engine runs at idling speed
       approx. 800...900 rpm.

• ‒ Run engine at idling 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. 340 °C.

Note:

This process can take a few minutes.

• ‒ Check the dynamic factor of Lambda probe before catalyst in display zone 3:
       Specification: 1.000... 4.000
• ‒ Continue to maintain idling speed until the specification "B1-P1 OK" appears in
       display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-20 .

If the display indicates as described:

• ‒ Press C key.

Work step 6: Lambda probe operating mode of diagnosis after catalyst

• ‒ Press keys 0, 4 and 3 for "Display group number 43" and confirm entry with Q key.

• ‒ Depress brake pedal and hold it down.

• Engine runs at idling speed
       approx. 800...900 rpm.

• ‒ Run engine at idling speed until the display
       in display zone 4 jumps from "Test OFF" to "Test ON".

Note:

This process can take a few minutes.

• ‒ Continue to maintain engine running at idling speed until the specification "B1-P2 OK" appears in
       display zone 4.

If the display does not indicate as described:

• ‒ Interrogate fault memory => Page 01-20 .

If the display indicates as described:

• ‒ Press C key.

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 and 4 for the function "Initiating basic settings" and confirm entry with Q key.

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

• ‒ Depress brake pedal and hold it down.

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

• ‒ Maintain the engine at increased 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. 340 °C.
• ‒ Check efficiency of catalyst in display zone 3:
       Specification: min. 1.00 %
• ‒ 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 01-20 .
• ‒ If no fault is stored in the fault memory:
• ‒ Switch off ignition.
• ‒ Perform a test drive at constant speed.
• ‒ Perform catalyst diagnosis again, if same result:
• ‒ Renew catalyst:
  =>Repair group 26; Removing and installing parts of the exhaust system

If the display indicates as described:

• ‒ Press ⇒key.

• The engine speed decreases to idling speed.

• ‒ Read readiness code=> Page 01-69