Checking the pressure relief valve in the version 1 cap

WARNING: This page is about a different car, the 2024 Audi A4 allroad. However, it is still accessible from the selected car via links, so may be relevant.

Fig 1: Coolant Expansion Tank

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-- Position the Cooling System Tester :V.A.G 1274B with the Adapter :V.A.G 1274B/15 on the cap.

-- Generate approximately 2 bar (29.01 psi) pressure using the cooling system tester hand pump.

Fig 2: Identifying VAG1274B & VAG1274B/15

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The pressure must lower to 1.8 to 1.6 bar (26.11 to 23.21 psi) and stay there.

-- If the pressure relief valve does not react as specified, replace the cap.

Checking the pressure relief valve in the version 2 cap:

Courtesy of AUDI OF AMERICA, LLC

-- Position the Cooling System Tester :V.A.G 1274B with the Cooling System Tester - Adapter :V.A.G 1274/9 on the cap -1-.

Fig 3: Identifying VAG1274B & VAG1274/9

Courtesy of AUDI OF AMERICA, LLC

The pressure release valve must open at 1.6 to 1.8 bar (23.21 to 26.11 psi).

-- If the pressure relief valve does not react as specified, replace the cap.