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Diagnosis and Repair of Faults Using a Tester

Model: Audi A4 B6 - Years 2000-2004
Part: Engine

Technology has advanced significantly: we can understand the origin of a fault using modern diagnostic testers (provided by manufacturers, generally to businesses). These should be connected to the control unit via a specific connector, and by connecting to it, we can read the stored faults. Without going into too many unnecessary explanations, this video will illustrate how the tester works, followed by the repair of the fault. First, upon starting the car, personally check for abnormal sounds or irregular engine operation (when you notice the check engine light comes on). If you want confirmation or wish to clear that light and understand why it comes on, take the tester and connect it to the diagnostic port (usually located under the driver's seat, near the fuse box, but its location varies by model). Once you identify the problem, if clearing it from the control unit does not resolve it and it reappears upon subsequent diagnosis, take action: in this case, we will find that it is an issue with the injection pump, located under a plastic tube. Remove it and disconnect the pump, replace it carefully to avoid breaking the tubes by forcing their insertion. Test everything and redo the diagnosis; it should be corrected. Remember that it is better to perform an initial diagnosis, clear the error, and then redo it later, as sometimes the error in the control unit has been there for a long time.

Updated on 9 February 2026 by ScegliAuto

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