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AV-SCANNER / Service function guides / Cooling and climate
This guide provides a complete diagnostic workflow for proving a head gasket failure before any teardown, covering combustion gas testing, cooling system pressure checks, and fluid analysis. It is written for working mechanics and experienced DIYers who need a repeatable, evidence-based method that works across gasoline and diesel engines. You will learn how to prepare the vehicle safely, run each test in the correct order, interpret the results with confidence, and avoid the common mistakes that lead to misdiagnosis. By the end, you will be able to confirm or rule out a head gasket failure and document your findings for the customer or your own repair decision.
Guidance is general and covers many makes. Exact procedures and values vary by model, so confirm them in the factory service information for your vehicle.
Download all 12 sections as a branded PDF to use in the workshop.
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