With Manufacturer's Scan Tool
Evaporative Emissions (EVAP) System, Checking
Special tools and equipment
- VAG1551 or VAG1552 scan tool with VAG1551/3 adapter cable
Test conditions
- Fuse 29 must be OK.
- No DTCs stored in DTC memory
- All electrical consumers, e.g. lights and rear window heating must be switched off
- If the vehicle is equipped with an air conditioner, this must be switched off.
- Intake air temperature less than 90°C display group 04, display zone 4
- Coolant temperature less than 95°C display group 04, display zone 3
- Throttle valve angle less than 10% display group 03, display zone 3
Functional check
- Connect V.A.G 1551 Scan Tool ((V.A.G 1552). Start engine and select engine electronics control module with "Address word" 01.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press keys 0 and 8 for function "Read measured value block" and confirm entry with Q key.
Indicated on display
Read measured value block
Input display group number XXX
- Press keys 0, 7 and 1 for "Display group number 71" and confirm entry with Q key.
Indicated on display
Read measured value block 71 ->
Reed closed Test OFF
Indicated on display
Read measured value block 71 ->
Reed closed Check END Syst. OK
- Check display in display field 1:
Display fields
If "Reed open" appears in display field 1:
- Briefly open tank cap so pressure in fuel tank can release, this will close Reed contact.
If the specification is attained
- Press button 4 for "Introduction of basic setting" function.
Indicated on display
System in basic setting 71 ->
Reed closed Test ON
- The test of the EVAP emissions system will be initiated. First of all the function of the Reed contact (in the Leak Detection Pump (LDP) -V144- will be checked by the control module.
- After approx. 60 seconds the Leak Dectection Pump (LDP) -V144-will be activated and build-up pressure in the fuel system.
Indicated on display
System in basic setting 71 ->
Reed open Syst. Test Test ON
- The test will be initiated after approx. 45 seconds (when there is sufficient pressure available in the fuel system).
Indicated on display
System in basic setting 71 ->
Reed open Check Test ON
- The Leak Detection Pump (LDP) -V144- switches off and the control module measures the time until the Reed contact closes.
Indicated on display
System in basic setting 71 ->
Reed closed Check.END Syst. OK
- Check display in display zones 3 and 4:
Display fields
If the specifications are obtained:
- Press -> key.
Indicated on display:
Rapid data transfer Help
Select function XX
- Press keys 0 and 6 for "End data output" function and confirm input with Q key.
- Switch ignition off.
Checking for leaks
If a small or large leak is detected during the check of the EVAP system, proceed as follows.
- Pull hose from leak detection pump off the EVAP canister and seal it, removing and installing components of EVAP system.
- Repeat functional check.
Is the malfunction still present:
- Remove rear left wheel housing liner.
- Check connecting lines and hoses between leak detection pump and EVAP canister.
Is the malfunction still present:
- Check whether fuel tank cap is fully closed or if seal is defective, replace if necessary.
- Check whether locking ring for fuel pump module is tight, it can be found under the luggage compartment floor trim, replace seal if faulty. Tighten locking ring using 3217 ring spanner. Check fuel supply and return lines on fuel pump module for leaks.
- Remove EVAP canister from spare wheel well and check for cracks and leaks, replace if necessary.
- Check connecting lines and hoses between EVAP canister and fuel tank flap unit/EVAP canister purge valve for EVAP canister.
- Check that hoses and hose clamps are tight.
- Repeat functional check.