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Diagnosis and Repair of the Secondary Air Injection System Fault

Model: Volkswagen Golf Golf IV, Golf 4, MK 4 - Years: 1997, 1998, 1999, 2000, 2001, 2002, 2003
Part: Checks and maintenance

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The secondary air injection system reduces harmful emissions by allowing further combustion of the engine's exhaust gases, injecting an oxidiser to aid in breaking down these gases. Using diagnostic software, connect to the vehicle's port and compare the manufacturer's data with the measurements obtained: once anomalies are detected, proceed with a physical analysis of the system.

Create a vacuum from a valve in the circuit and check for leaks. If the vacuum is not maintained, it indicates a leak in the circuit, and you should search for faults in the pipes.

Once the damaged pipes are found and replaced, conduct a new check using the software: if the obtained data matches the declared values, the problem is resolved.


Updated on 8 February 2026 by ScegliAuto


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by ScegliAuto

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