With Manufacturer's Scan Tool
Evaporative Emissions System, Checking For Leaks
Special tools and equipment
- V.A.G 1551 Scan Tool
NOTE: The vehicle system tester V.A.G 1552 can be used instead of the VAG 1551 scan tool, however a print-out is not possible.
- V.A.G 1551/3 Cable
Test conditions
- Fuse No. 43 must be OK.
- No DTC stored in DTC memory
- All electrical consumers, e.g. lights and rear window defroster must be switched off.
- If the vehicle is equipped with an air conditioner, this must be switched off.
- Throttle valve angle less than 10 degree % display group 03, display zone 3
- Coolant temperature less than 80 degrees C, See display group 04, display zone 3.
- Intake air temperature less than 60 degrees C, See display group 04, display zone 4.
Functional check
- Connect VAG 1551 Scan Tool (or V.A.G 1552). Start engine and select engine control module with the "Address word" 01.
Connecting VAG 1551 scan tool and selecting engine electronics control module
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 open Test OFF
- Press key 4 for "Introduction of basic setting" function.
Indicated on display
System in basic setting 71
Reed open Test ON
Indicated on display
System in basic setting 71
Reed closed Test ON
The test of the evaporative emissions system will be initiated. First of all the function of the Reed contact (in the LDP - V144-) will be checked by the control module.
Indicated on display
System in basic setting 71
Reed closed Syst. Test Test ON
- After approx. 10 seconds the 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. 50 seconds (when there is not sufficient pressure available in the fuel system can last up to 120 seconds).
Indicated on display
System in basic setting 71
Reed open Check Test ON
The 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:
Specified value display field 3: Meas.END
Specified value display field 4: Syst. OK
If the specifications are not attained:
- Checking for proper seal. Testing and Inspection
If the specifications are obtained:
- Press -> key.
- Press keys 0 and 6 for function "End output" and confirm entry with Q key.
- Switch off ignition.
Checking for leaks
If a small or large leak is detected during the check of the evaporative emissions system, proceed as follows.
- Switch ignition off.
- Check whether sealing cap of fuel tank is completely closed or seal is leaking, replace if necessary.
Is the malfunction still present:
- Repeat functional check.
- Fold rear seat bench forward.
- Remove cover below seat bench.
- Check locking ring for fuel pump for tightness or if seal is faulty and replace if necessary. Tighten locking ring using 3217 special tool. Check supply and return lines of at fuel pump for proper seal.
- Repeat functional check.
Is the malfunction still present:
- Remove rear right wheel housing liner:
- Check pressure hose between LDP and EVAP canister for proper seal.
- Check wires and wire connections between EVAP canister and tank flap unit or tank ventilation valve for proper seal.
- Repeat functional check.
- Is the malfunction still present:
- Remove EVAP canister and check for tears and leaks, replace if necessary.
- Repeat functional check.