Evaporative Emissions System: Testing and Inspection
- Observe safety precautions.
- Observe rules for cleanliness.
NOTE:
- All hose connections are secured with clips.
- Always replace seals and gaskets.
Test requirements
- No DTCs in DTC memory
- Electrical consumers switched off (radiator fan must NOT run during test)
- A/C switched off
- Intake Air Temperature (IAT) less than 90 °C See display group 004, display field 4
- Coolant Temperature less than 95 °C See display group 004, display field 3
- Throttle valve angle less than 10 display group 003, display field 3
- Connect VAS5051 tester to vehicle with VAS5051/1 diagnostic wire. Alternately, VAG1551 scan tool can also be attached using VAG1551/3A adapter.
NOTE: The following description only explains implementation of On Board Diagnostic (OBD) using VAG1551 scan tool. When using the VAS5051 tester, observe the tester's instructions for use.
- Start engine and run at idle.
- Press button 1 to select "Rapid data transfer" operating mode 1.
Indicated on display
Rapid data transfer HELP
Insert address word XX
- Press buttons -0- and -1- to select "Engine Electronics" and press -Q- button to confirm input.
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press buttons -0- and -8- to select "Read Measuring Value Block" and press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block
Input display group number XXX
- Press buttons -0- , -7- and -1- for "display group number 071" and press -Q- button to confirm input.
Indicated on display
Read Measuring Value Block 71 ->
Reed cl Abort Test OFF
NOTE:
- If "Reed cl" (closed) is displayed, continue test.
- "Abort" does not always appear on display.
- If display indicates "Reed open," briefly open and close fuel filler cap to release pressure from fuel tank. This will close the reed contact. Continue test as follows:
- Press button 4 to select "Initiating basic setting" operating mode 4.
When indicated on display
System in Basic Setting 71 ->
Reed closed Test ON
Evaporative Emission (EVAP) canister purge regulator valve -N80- will be opened briefly to release pressure (purge) in system, and the Evaporative Emission (EVAP) canister purge solenoid valve -N115- will be closed.
Then the Leak Detection Pump (LDP) -V144- will be activated (the process will last about 60 seconds).
Indicated on display
System in Basic setting 71 ->
Reed open Syst.Test Test ON
- System is performing a system test. Then the Leak Detection Pump (LDP) -V144- will start up. It will shut off when pump time has run out.
- The process will last about 60 seconds.
Indicated on display
System in Basic Setting 71 ->
Reed open Check Test ON
Measuring phase begins. LDP is switched off and the Engine Control Module (ECM) checks whether the reed contact closes within 10 seconds.
If reed contact does not close within 10 seconds:
Indicated on display
System in Basic setting 71 ->
Reed open Check. END Syst.OK
System is sealed properly, test is terminated.
- Press -> button.
- Press buttons -0- and -6- to select "End output" and press -0- button to confirm input.
If reed contact closes within 10 seconds:
Leak Detection Pump (LDP) -V144- will pump four additional strokes for an additional measurement. The Engine Control Module (ECM) compares the time required for these four strokes and time until closure of the reed contact.
Indicated on display
System in Basic Setting 71 ->
Reed cl Sm. Leak.END Syst.n.OK
System has a small leak (smaller than 1 mm in diameter).
Indicated on display
System in Basic Setting 71 ->
Reed cl.Lg.Leak.END Syst.n.OK
System recognized a large leak.
- Press -> button.
- If system has detected a small or large leak, check fuel supply system and tank ventilation systems for leaks and repair as necessary.
- After repairs are completed, repeat leak test.
Checking fuel supply and ventilation Systems for leaks
NOTE: The following describes areas in the fuel supply and ventilation systems that should be checked for possible leaks. After making necessary repairs, perform leak test again to ensure that all leaks were successfully repaired.
- Switch ignition off.
- Check whether fuel filler cap was completely closed for test.
- Check seal of fuel filler cap for damage. Replace if necessary.
- Check whether seals under connection flanges are OK and union nuts are properly tightened. Also check fuel line connections.
- Remove rear seat bench.
- Unscrew cover at right beneath rear seat bench.
NOTE: Observe installation notes for connector flanges. Refer to "Fuel Pump, Removing and Installing (Front wheel drive)", Service and Repair
- Visually check all wires and hose connections of fuel supply system and replace loose 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, under front right wheel housing liner)
- Line from fuel tank to Evaporative Emission (EVAP) canister (under cover for EVAP canister)
- Lines from EVAP system (under right wheelhousing liner)
- Fuel lines to engine
NOTE: Leaks at lines and components of fuel supply system can sometimes be located using a non-flammable, environmentally sound leak detection spray. For this, initiate leak testing several times in sequence to build pressure in the system. Leaks can be detected via bubbles forming at the leak.
- 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-
- Evaporative Emission (EVAP) canister purge solenoid valve -N115-
NOTE:
- Because of the 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 3093 hose clamps and initiate the leak detection diagnostic. If the 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.
- Checking Evaporative Emission (EVAP) canister purge regulator valve -N80-
- For leaking Evaporative Emission (EVAP) canister purge solenoid valve -N115-, replace O-rings, Fig. 9. Service and Repair