Display Group 024

DISPLAY GROUP 03
Evaporative Emissions System Diagnostic

NOTES:
^ Use display group 024 to carry out a selective diagnostic if the value of the Evaporative Emissions (EVAP) system flow diagnostic is not set to "0" in display group 023, display field 7 during reset of the "Readiness Code" and/or there is a malfunction (DTC) in the DTC memory that relates to the EVAP system.
^ If the diagnostic conditions are fulfilled, the ECM checks the EVAP system at each engine start-up. The pressure difference between EVAP Canister and EVAP canister purge regulator valve is measured via the EVAP System Differential Pressure Sensor.
^ The diagnostic conditions are fulfilled (diagnostic is active) only during a drive at 50-62 mph (80-100 km/h) for approx. 1-1/2 to 5 minutes in 4th or 5th gear To get a diagnostic result, the EVAP system pressure is measured with the EVAP canister purge regulator valve open and closed. EVAP system pressure is first measured with the EVAP canister purge regulator valve closed. The easiest way to get the EVAP canister purge regulator valve to close is via a prior deceleration fuel shut-off. If there are difficulties in closing the EVAP canister purge regulator valve via deceleration fuel shut-off it can also be closed by performing this display group ("Basic Setting" function 04, display group 024). Once EVAP system pressure is measured with the EVAP canister purge regulator valve closed, the pressure must be measured again in "Read Measuring Value Block" function 08 with EVAP canister purge regulator valve completely open.
^ Diagnostic is recognized as OK if the measured EVAP system pressure in display field 7 is greater than the calculated EVAP system minimum pressure in display field 2.
^ If the EVAP system is recognized as OK during the first diagnostic, diagnostic is ended. If the EVAP system is recognized as not OK, diagnostic will continue.
^ If diagnostic is immediately repeated after an OK diagnosis, switch engine off then restart.

DISPLAY OVERVIEW

VAG 1551 Display Overview, Display Group 024:

Note For Display Field 2:
The pressure that is displayed is calculated using the amount of air flow through the Mass Air Flow (MAF) sensor at the time of the diagnosis.

Note For Display Field 2:

Diagnostic Status And/or Result Display:

Interpreting the 4-Digit "Diagnostic Status and/or Result"