With Manufacturer's Scan Tool
Evaporative Emissions System, Leak Testing
Special tools, equipment, test and inspection devices; required accessories
- V.A.G 1551 scan tool
NOTE: The VAG 1552 system tester may also be used in place of the VAG 1551 scan tool, except that no printout can then be made.
- V.A.G 1551/3 lead
Test conditions
- Fuse no. 43 must be OK.
- No fault in fault memory:
- Anything using electricity, such as lights and rear window heater, must be turned off.
- If the vehicle has air conditioning, it must be off.
- Throttle valve angle less than 10 % display group 03, field 3
- Engine coolant temperature less than 99 °C See display group 04, field 3
- Intake air temperature less than 95 °C See display group 04, field 4
Functional test
- Connect V.A.G 1551 (or VAG 1552) scan tool. Leave engine running and select engine control module using address word 01.
Indicated on display:
Rapid Data Transfer HELP
Select Function XX
- Press keys "0" and "8" for function "Read Measuring Value Block" and acknowledge entry by pressing "Q."
Indicated on display:
Read Measuring Value Block
Enter Display Group No. XXX
- Press keys "0", "7" and "1" for display group 71 and acknowledge entry by pressing "Q."
Indicated on display
Read Measuring Value Block 71 ->
Reed closed Abort Test OFF
or
Indicated on display
Read Measuring Value Block 71 ->
Reed closed Messg.END Syst.OK
- Check display in field 1:
If "reed open" appears in field 1:
- Briefly open fuel tank cap to reduce tank pressure. This will close reed contact.
If the specification is attained:
- Press "4" for function "start basic setting."
Indicated on display (1-4 = display fields).
System in basic setting 71 ->
1 2 3 4
- Let engine idle until "Syst. OK" is displayed in field 4.
If "reed open" appears in field 1:
- Briefly open fuel tank cap to reduce tank pressure. This will close reed contact.
If the diagnosis is started by the engine control module, the display in field 4 will jump from "Test OFF" to "Test ON".
NOTE:
- If field 4 switches from "Test ON" to "Test OFF" during the diagnosis, repeat the leak testing.
- The fuel tank cap must be opened briefly before the diagnosis can be repeated.
If the indicator does not behave as described:
If the specifications were attained:
- Press -> button.
- Press keys "0" and "6" for function "end output" and acknowledge with "Q."
- Turn off ignition.
If the specifications were not attained:
- Press "8" for function "Read Measuring Value Block".
Indicated on display
Read Measuring Value Block 71 ->
Reed open Messg. END Syst. OK
- Press "1" for display group 70 and acknowledge with "Q."
Indicated on display (1-4 = display fields)
Read Measuring Value Block 70 ->
1 2 3 4
- Press "4" for function "basic setting." Leak test is started.
NOTE: No load may be produced during this diagnosis. Otherwise the diagnosis will be stopped and can only be started again after applying the accelerator.
Indicated on display (1-4 = display fields)
System in Default 70 ->
1 2 3 4
If the diagnosis is started by the ending control module, the display in field 4 will jump from "Test OFF" to "Test ON".
- Let engine idle until specification "TEV OK" is displayed in field 4.
NOTE: If the display jumps from "Test ON" to "Test OFF" during the test, the test can be repeated by a short application of the accelerator.
If "TEV nOK" is displayed in field 4:
- Start output DTM and trigger solenoid valve 1 for charcoal filter (N80):
- Read readiness code:
- If fault memory has been erased or engine control module was separated from positive voltage supply, readiness code must be regenerated:
If the specification "TEV OK" was achieved:
- Press -> button.
- Press keys "0" and "6" for function "end output" and acknowledge entry with "Q."
- Turn off ignition.
Checking sealing quality of system
Proceed as follows if a fine or large leak was found during the functional test of the charcoal canister assembly.
- Check whether cap of fuel tank is completely closed and whether sealing ring is leaking; replace if necessary.
- Repeat functional test.
If the malfunction is still present:
- Fold rear seat bench forward.
- Remove cover under seat bench.
- Check whether union nut of fuel delivery module is tight and whether sealing ring is leaking; replace as necessary.
- Retighten union nut with wrench 3217. Check feed and return lines of fuel delivery module for leaks.
- Repeat functional test.
If the malfunction still exists:
- Remove rear right wheel housing liner:
- Check discharge hose for leaks between leak detection pump and charcoal canister, item -5-. Replace if necessary
- Check lines and joints for leaks between charcoal canister and fuel filler door and solenoid valve 1. Refer to "Evaporative Emissions System, Diagram", Diagrams
- Repeat functional test.
If the malfunction is still present:
- Remove charcoal canister and check for cracks and leaks; replace if necessary.
- Repeat functional test.