Diagnostic Mode 8: Tank Leak Test

2003 Volkswagen Passat Sedan (3B3) V6-2.8L (ATQ)SECTION Diagnostic Mode 8: Tank Leak Test


Diagnostic mode 8: Tank leak test

Function
This diagnostic mode checks the fuel system for leaks.

NOTE:
- The Evaporative Emission (EVAP) Canister Purge Regulator Valve -N80- and Leak detection pump (LDP) -V144- seal the tank system.
- Pressure of (max. 70 mbar) can be applied to the fuel system via the test connection (in engine compartment, right) and using engine leak detection spray (e.g.: G 001 800 A1) leaks can be detected.

Test requirements
- There must not be any DTCs stored in DTC memory, Diagnostic mode 3: Check DTC memory.
- Coolant temperature must be 80 to 110 degrees C, Diagnostic mode 1: Check measuring values; PID 5, Coolant temperature. Diagnostic Mode 1: Check Measuring Values
- Intake Air Temperature (IAT) must not be above the maximum of 60 degrees C, Diagnostic mode 1: Check measuring values; PID 15, Intake Air Temperature (IAT). Diagnostic Mode 1: Check Measuring Values
- Throttle valve angle 12.0 to 16.0 %, Diagnostic mode 1: Check measuring values; PID 17: Throttle valve position (absolute) Diagnostic Mode 1: Check Measuring Values

Function test
- Connect diagnostic tester. Diagnostic Tester, Connecting
- 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 ventilation test at idle.






NOTE:
- 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 at idle for at least 15 minutes.

If specified value is obtained:
- End diagnosis and switch ignition off.

If specified value is not obtained:
- EVAP canister system, checking for proper seal. Testing and Inspection
- Leak detection pump (LDP) -V144-, checking. Testing and Inspection

RENDER: 1.0x

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When to See a Mechanic

Stop DIY work and contact a certified mechanic immediately if any of the following apply:

  • You smell fuel, burning insulation, or see smoke.
  • Brakes feel soft, pull hard to one side, or make grinding noises.
  • The engine overheats, stalls repeatedly, or misfires under load.
  • You are missing required tools, torque specs, or safe lifting equipment.
  • You are not confident in the next step or safety outcome.