With Generic Scan Tool

EVAP Canister System, Checking For Proper Seal

NOTE:
- Secure all hose connections using hose clamps appropriate for the model type.
- Always replace seals and gaskets.

Test sequence
- Connect diagnostic tester. Diagnostic Tester, Connecting
- Start engine and let run at idle for at least 15 minutes.
- In diagnostic function "33 - OBD", select "Mode 8: Tank leak test". Diagnostic Mode 8: Tank Leak Test
- Select the "Test-ID 01: Tank leak test" and check specified value at idle.
- Specified value: Test OK

NOTE:
- If the accelerator pedal is depressed during the test, the test will be aborted.
- To repeat the tank leak test, switch ignition off and start engine again and let run at idle.

If specified value is obtained:
- End diagnosis and switch ignition off.

If specified value is not obtained:

Checking fuel supply and ventilation systems for leaks
- Check whether fuel filler cap was completely closed for test.
- Check seal of fuel filler cap for damage. Replace if necessary.
- Disconnect and seal connection hose -item 11-, of Leak detection pump (LDP) -V144- at EVAP canister.
- Repeat function test.

If malfunction persists:
- Remove EVAP canister cover at bottom of spare tire well.
- Remove sealing pieces above ventilation lines.
- Check connection pipes and hoses between Leak detection pump (LDP) -V144- and EVAP canister for proper seal EVAP canister/tank leak diagnostic system - component overview.
- Repeat function test.

If malfunction persists:

Front Wheel Drive (FWD) vehicles:
- Unscrew cover for connector flange of fuel pump below the luggage compartment carpet.

All Wheel Drive (AWD) vehicles:
- Rear connector flange: Remove luggage compartment carpet. Unscrew connector flange cap.

NOTE: To do so, remove luggage compartment floor on the Avant.

- Front connector flange: Remove rear seat, unscrew cap above connector flanges.

All:
- Check whether seals under connection flanges are OK and union nuts are properly tightened. Also check fuel line connections.
- Visually check all wires and hose connections of fuel supply system and replace leaking lines, e.g.:
- Line from EVAP canister to Evaporative Emission (EVAP) Canister Purge Regulator Valve (in engine compartment)
- Lines from EVAP canister to Leak Detection Pump (LDP)
- Line from fuel tank to Evaporative Emission (EVAP) canister (under cover for EVAP canister)
- Lines from EVAP system (under rear right wheel housing liner)
- Fuel lines to engine

NOTE:
- Leaks at lines and components of fuel supply system can sometimes be located using a nonflammable, environmentally sound engine leak detection spray (e.g. G 001 800 A1).
- Pressure of (max. 70 mbar) can be applied to the fuel system via the test connection (in engine compartment, right). Leaks can be determined using engine leak detection spray. When doing this, bubbles form at leaking areas.

- Repeat function test.

If malfunction persists:
- Visually check components of fuel supply system and EVAP system.
- Fuel tank
- EVAP canister
- Leak Detection Pump (LDP) -V144-
- Evaporative Emission (EVAP) canister purge regulator valve -N80-

NOTE:
- Also check vacuum hose setup from engine compartment to leak detection pump or to exhaust flap (only vehicles with Front Wheel Drive (FWD)) for proper seal
- Because of shape or function of these components it is not always possible to find leaks by applying spray. It may be necessary to clamp off the relevant component using 3094 hose clamps and initiate leak detection diagnostic. If leak is no longer detected, the component that was clamped off is faulty. If clamp is placed directly on the diagnostic pump and a leak is still detected, then the diagnostic pump itself is leaking.
- Observe installation notes for connector flanges.

Final procedures
After repair work, the following work steps must be performed in the mentioned sequence:
1 - Check DTC memory, Diagnostic mode 3 - Check DTC memory. Diagnostic Mode 3: Check DTC Memory
2 - Erase DTC memory, diagnostic mode 4 - Reset/erase diagnostic data. Diagnostic Mode 4: Reset/Erase Diagnostic Data
3 - Generate readiness code. Readiness Code, Generating

- End diagnosis and switch ignition off.