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.

• Depending on scan tool and protocol used, the information in diagnostic mode 01 may be referred to by different names such as Test-ID (TID), Hex-ID, Component-ID (CID), or On-Board Diagnostic Monitor Identifier (OBDMID).

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.

• Evaporative Emission (EVAP) Canister Purge Regulator Valve 2 ( N333) and fuel system Leak Detection Pump (LDP) ( V144) seal fuel system.

• Using engine leak detection spray (e.g.: G 001 800 A1) leaks can be detected.

Test Conditions

• There must not be any DTCs stored in DTC memory => [ Diagnostic Mode 03 - Read DTC Memory ] , Diagnostic mode 3: Check DTC memory.

• Coolant temperature must be 80 to 110° C => [ Diagnostic Mode 01 - Read Current System Data ] , Diagnostic mode 1: Check measured values; PID 05, 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 measured values; PID 15, Intake air temperature.

Function Test

- Connect diagnostic tester.

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

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

- Select measuring value "Test ID 01: Tank leak test".

- Check specified value of tank leak test at idle.

Evaluation test-ID 01: Tank leak test





• During tank leak test, "test function active" is limited to approx. 12 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 at idle for at least 15 minutes.

- End diagnosis and switch ignition off.

If a leak is detected:

- EVAP canister system, checking for proper seal => [ EVAP System, Checking for Proper Seal ] Component Tests (VAG Code Tests).

- Evaporative Emission (EVAP) Canister Purge Regulator Valve 2 ( N333), checking => [ EVAP Canister Purge Regulator Valve 2, Checking ] Component Tests (VAG Code Tests).

- Fuel system Leak Detection Pump (LDP) (V144), checking. Refer to Repair Information.

- Erase DTC memory of Engine Control Module => [ Diagnostic Mode 04 - Erase DTC Memory ] , Diagnostic mode 4: Reset/erase diagnostic data.

- Generate readiness code => [ Readiness Code, Generating ] Monitors, Trips, Drive Cycles and Readiness Codes.