Service function guideDiesel Common Rail Diagnosis

This guide equips professional technicians with a structured method for diagnosing diesel common rail faults by reading live rail pressure and injector return data, covering system theory, preparation, step-by-step procedures, result interpretation, and cross-vehicle variations. It is written for working mechanics who already understand basic diesel engine operation and have access to a scan tool with live data capabilities. After completing the procedure, the reader will be able to distinguish between high-pressure pump, rail pressure regulator, injector, and low-pressure supply faults using measured values rather than guesswork. The guide also addresses common mistakes, troubleshooting when data is unavailable, and aftercare steps to confirm a lasting repair.