Diagnostic Mode 08 - Request Control of on-Board System, Test or Component

Diagnostic Modes 01 - 09

Diagnostic Mode 08 - Request Control of On-Board System, Test or Component

The information provided in Modes 01 through 09 displays the various levels of emission related data that may be monitored, as well as the ability to retrieve and read stored DTC trouble codes, erase stored DTC trouble codes, generate readiness codes, and select the various PIDs and Test-IDs used within the modes to monitor the engine, and emission related component parameters.

Diagnostic Mode 08 is used to control the operation of an on-board system, test or component. A Mode 8 service can be used to turn on-board system ON or OFF, or to cycle an on-board system, test or component ON or OFF for a specific period of time. The service can also be used to request system status or to report test results.

Diagnostic Mode 08, TID $01

Diagnostic Mode 08, TID $01 is used to determine if the evaporative system may be leaking.

• The Evaporative Emission (EVAP) Canister Purge Regulator Valve (N80)- and Leak detection pump (LDP) (V144) seal the tank system.

Test Prerequisites

• Coolant temperature must be 80 to 110° C => [ Diagnostic Mode 01 - Read Current System Data ] , Diagnostic mode 1: Check measured values; PID 5, Coolant temperature.

• Intake air temperature must not be above the maximum of 60° C => [ Diagnostic Mode 01 - Read Current System Data ] , Diagnostic mode 1: Check measuring values; PID 15, Intake air temperature.

• Throttle valve angle 12.0 to 16.0% => [ Diagnostic Mode 01 - Read Current System Data ] , Diagnostic mode 1: Check measured values; PID 17: Throttle valve position (absolute)

Function Test

- Connect diagnostic tester.

- Start engine and let run at least 15 minutes at idle.

- Under address word 33, select "Diagnostic mode 8: Tank leak test".

- Measuring value "Test-ID 01: select Tank leak test".

- Check specified value of tank leak test at idle.





• The function test can take a few minutes.

• 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 15 minutes at idle.

If specified value is obtained:

- End diagnosis and switch ignition off.

If specified value is not obtained:

- EVAP canister system, checking for proper seal => [ EVAP System Diagnostic Leak Test, Performing ] Component Tests (VAG Code Tests).

- Leak detection pump (LDP) (V144), checking => [ Leak Detection Pump, Checking ] Component Tests (VAG Code Tests).