Quick Test of the Fuel Tank System

Quick test of the fuel tank system

General information about testing the fuel tank system
The engine management system has a built-in function for carrying out a quick check of fuel tank system sealing. By activating the function, the control module is able to determine whether the fuel tank system including its components and hoses are free of faults and whether there is any leakage.
For further information about the fuel tank system diagnostic, see Leak diagnostics Leak Diagnostics.

Component positioning
1. Canister purge (CP) valve
2. EVAP canister reservoir
3. EVAP canister shut-off valve
4. Air cleaner for fresh air
5. Fuel tank pressure sensor
6. On board fuel vapor recovery (ORVR) valve
7. Roll-over valve.
For further information about the location of components, see Location of components Locations.






Continue - Starting the quick test

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Starting the quick test




Note! Certain conditions must be met for the diagnostic to start:
- Engine speed < 3500 rpm
- Engine coolant temperature (ECT) > 30°C
- Normal battery voltage
- Quantity of fuel in the tank < 60 liters
- Height above sea level < 2500 m.

- Start the engine. Allow the engine to idle.
Start the quick test.

Hint: If the EVAP canister is overfull, the engine may start to run unevenly and possibly even stall. If this happens, restart the engine and the quick test. Let the engine idle until the status changes from inhibited to running. Then increase the engine speed (RPM) to between 1500-2000 rpm. Maintain this engine speed (RPM) until the status changes to finished.

Information
In the event of leakage in the fuel tank system, only 1 diagnostic trouble code (DTC) will be stored (only data from status window DTC1 will be displayed). The 2nd status window remains empty.
If there is a smaller leak that is not large enough for a diagnostic trouble code (DTC) to be stored, 2 diagnostic trouble codes (DTCs) and the test values will be displayed. These test values must be checked to ensure that they correspond with the values in the table. See Reading off the test results / the fuel tank values Reading Off the Test Results / the Fuel Tank Values.

Other parameters:
- EVAP canister shut-off valve. Closes when it is active, ON (red line)
- Fuel tank pressure (yellow line)
- Canister purge (CP) valve (green line).

Hint: When the curves go outside the measurement range, press "AUTORANGE" so that they are visible within the measurement range again.

The quick test process
When the quick test is complete, the result is displayed in status window DTC1 and where applicable DTC2.
If a fault was detected during the test, a diagnostic trouble code (DTC) and a test value will be displayed. Fault-tracing must then be carried out by selecting this test.
If no faults were found during the test, diagnostic trouble codes (DTCs) will be displayed in both the status windows instead. The test value must then be compared with the quantity of fuel in the fuel tank to determine whether there is a small leak that the quick test was unable to detect. (See the information above).






Continue - DONE

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