FUEL SYSTEM, CHECKING FOR LEAKS WITH Smoke Tester: VAS 523 005

WARNING: This page is about a different car, the 2023 Audi S3, 2023 Audi RS 3, 2023 Audi A3 Quattro, and 2023 Audi A3. However, it is still accessible from the selected car via links, so may be relevant.

Special tools and workshop equipment required

Diagnostic Smoke® Machine:VAS 523 005

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Connector:VAS 523 005/4

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Adapter:VAS 523 005/5 , :VAS 523 005/6 or :VAS 523 005/7 (depends on the diameter of the bleeder line)

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Plug:VAS 523 005/8

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Protective eyewear (yellow)
Diagnostic Smoke® Machine:VAS 523 005 operating instructions

Test Conditions:

Guided Fault Finding was performed using the Vehicle Diagnostic Tester.
A leak must have been detected by the Fuel Tank Leak Detection Module -GX36-.

NOTE:

The "small leak" DTC means that the total of all leaks is equal to a leak with a diameter greater than 0.5 mm.

Diagnostic Smoke® Machine:VAS 523 005 , Preparing:

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-- Check the water separator -A- on the smoke tester. Drain the water separator if necessary.

-- Connect the pressure hose to the connection -B-.

-- Use the dipstick -D- to check if there is enough fluid in the Diagnostic Smoke® Machine.

-- Connect the power supply on the Diagnostic Smoke® Machine -C- to the jump start point on the vehicle.

-- Disconnect the breather line in the engine/motor compartment -1- and check which Connection Set must be used.

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Diagnostic Smoke® Machine and Adapter, Checking for Leaks:

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-- Connect the Connector -A- and Adapter -B- as shown.

-- Open the shut-off valves -C-.

-- Connect the measuring hose on the smoke tester to the hose -D-.

-- Set the valve -A- to "TEST".

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-- Switch on the Diagnostic Smoke® Machine -B-. The adapter is now going to be filled with test gas.

-- Watch the pressure gauge -C- and the flow meter -D-.

If the pressure rises to 35 mbar and the ball in the flow meter sinks to >>zero<<, then there are no leaks in the Diagnostic Smoke® Machine and the Adapter and they can be used.

-- Switch off the Diagnostic Smoke® Machine.

EVAP Canister Purge Regulator Valve 1 -N80-, Checking for Leaks:

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-- Connect the Adapters to the bleeder lines -1- and -2- on the vehicle as shown.

-- Connect the measuring hose on the Diagnostic Smoke® Machine to the Connector -3-.

-- Close the shut-off valve -A- (line to the EVAP canister).

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-- Set the valve -A- to "TEST".

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-- Switch on the Diagnostic Smoke® Machine. The hose to the Solenoid Valve -- will then be filled with smoke.

If the pressure rises to 35 mbar and the ball in the flow meter sinks to >>zero<<, then the EVAP Canister Purge Regulator Valve 1 -N80- has no leaks and is OK.

-- Switch off the Diagnostic Smoke® Machine.

EVAP Canister, Fuel Tank and Lines, Checking for Leaks:

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-- Re-open the shut-off valve -A- (line to the EVAP canister).

-- Fill the fuel system with smoke by setting the valve -A- to "SMOKE" and switching on the Diagnostic Smoke® Machine.

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-- Remove the air filter -1- for the EVAP system -1-. Refer to EVAP SYSTEM AIR FILTER, REMOVING AND INSTALLING .

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-- Continue filling the fuel system with smoke, until it come out of the vent hose -3-.

-- If smoke escapes, seal the connection with the Plug:VAS 523 005/8 .

-- Set the valve -A- to "TEST" and continue filling the fuel system.

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-- Watch the pressure gauge -C- and the flow meter -D-.

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If the pressure rises to 35 mbar and the ball in the flow meter sinks below the >>0.25 mm mark<< -arrow-, then the fuel system is filled.

NOTE:

If a sporadic fault is suspected, move the lines, hoses, and the cap. If the flow meter indicates a change when a component is moved, check that component.

Depending on the fuel level in the fuel tank, it may take up to five minutes to fill with smoke.

The Diagnostic Smoke® Machine has an automatic shut-off. The Diagnostic Smoke® Machine may need to be switched on again if it shuts off.

-- Once the flow meter has stabilized, switch the Diagnostic Smoke® Machine off and check the pressure gauge.

The pressure must not drop below 30 mbar after five minutes.

If the pressure drops or if no pressure develops, then locate the leak as follows:

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-- Set the valve -A- to "SMOKE" and fill the fuel system with smoke.

-- Check all the lines, hoses and the fuel filler cap for escaping smoke.

-- Shine a flashlight on all components and hoses, because the smoke is more visible in white light.

-- Use the laser to narrow down the location of the leak. The laser beam will >>light up<< in the smoke and be visible.

-- The smoke contains a contrast agent. The contrast agent will be visible at the location of the leak under ultraviolet light.

-- The installation opening inside the passenger compartment must be opened to check the flange on the fuel pump and fuel filter.

-- Replace any leaking hoses or components.

After completing the work, perform the Check tank ventilation system for leaks guided function with the Vehicle Diagnostic Tester.