With Manufacturer's Scan Tool
Evaporative Emissions (EVAP) System, Checking
Special tools, test equipment and auxiliary items
- VAG 1551/1552 Scan Tool
NOTE: The VAG 1552 Scan Tool can be used instead of the VAG 1551; however, a print-out is not possible.
- VAG 1551/3B adapter cable
Checking requirements
- All fuses must be OK.
- No malfunctions stored in DTC memory
- All electrical consumers switched OFF, e.g. lights and rear window heater must be OFF
- A/C switched OFF, if equipped.
- Throttle valve angle less than 10 % display group 03, display zone 3
- Engine Coolant Temperature less than 95 °C See display group 04, display zone 3
- Intake Air Temperature 90 °C maximum See display group 04, display zone 4
Test sequence
- Connect VAG1551/1552 Scan Tool.
- Start engine and let idle.
- Press 0 and 1 buttons to select Address word 01 "Engine electronics". Press Q button to confirm input
Indicated on display
Rapid data transfer HELP
Select function XX
- Press 0 and 8 buttons to select Function 08: "Read measuring value block"
- Press Q button to confirm input
Indicated on display
Read measuring value block
Input display group number XXX
- Press 0, 7 and 1 buttons to select "Display group 71"
- Press Q button to confirm input
Indicated on display
Read measuring value block 71 ->
Reed closed Terminated Test OFF
or
Indicated on display
Read measuring value block 71 ->
Reed closed Check END System OK
- Check display in zone 1:
If "Reed open" appears in display group 1:
- Briefly open fuel tank cap to release pressure in fuel tank.
- Reed switch will close
If specification is obtained:
- Press 0 and 4 buttons to select Function 04 "Basic setting".
- Press Q button to confirm input
- Press 0, 7 and 1 buttons to select "Display group 71"
- Press Q button to confirm input
Indicated on display
System in basic setting 71 ->
Reed closed Test ON
- Evaporative emissions system test will begin. First, the Function of the Reed switch (in Leak Detection Pump V144) will be checked by the ECM.
- After approx. 10 seconds the Leak Detection Pump V144 will be activated and pressure will build-up in the system.
Indicated on display
System in basic setting 71 ->
Reed open System Test Test ON
- The test will be initiated after approx. 50 seconds, when sufficient pressure has built up in the fuel system; however, it could take as long as 120 seconds to build the pressure if the fuel level is low.
Indicated on display
System in basic setting 71 ->
Reed open Check Test ON
- The Leak Detection Pump V144 switches OFF and the ECM measures the time until the Reed contact closes.
Indicated on display
System in basic setting 71 ->
Reed closed Check END System OK
- Check display in zones 3 and 4:
If the specification are obtained the display zone 3 shows "END of Test" and display zone 4 "System OK":
- Press -> button.
- Press 0 and 6 buttons to select Function 06: "End transfer"
- Press Q button to confirm input
- Switch OFF ignition.
If specifications not obtained:
- Press 0 and 8 buttons to select Function 08: "Read measuring value block"
- Press Q button to confirm input
Indicated on display
Read measuring value block
Input display group number XXX
- Press buttons 0, 7 and 0 to select "Display group 70"
- Press Q button to confirm input
Indicated on display (1 to 4 = Display zones)
Read measuring value block 70 ->
1 2 3 4
- Press 0 and 4 buttons to select Function 04: "Basic setting"
- Tank vent valve diagnosis will be initiated
NOTE: Engine must not be under load during this diagnosis because diagnosis will be interrupted and will not restart until engine is accelerated.
Indicated on display (1 to 4 = Display zones)
System in basic setting 70 ->
1 2 3 4
- When the diagnosis is initiated by the Engine Control Module, the display in display zone 4 jumps from "Test OFF" to "Test ON"
- Run engine at idle until specification "TEV OK" is shown in display zone 4.
NOTE: If display changes from "Test ON" to "Test OFF" during test, briefly accelerate engine and test will repeat.
If "TEV not OK" appears in display zone 4:
- Perform Output Diagnostic Test Mode and activate the EVAP canister purge regulator valve N80:
- Display Readiness code:
- Readiness code must be reset if ECM is subject to low voltage with ignition ON or if fault memory is erased.
If specification "TEV OK" is obtained:
- Press -> button.
Indicated on display
Rapid data transfer HELP
Select function XX
- Press 0 and 6 buttons to select Function 06: "End transfer"
- Press Q button to confirm input
- Switch OFF ignition.