Accessory guideDiesel Injector Leak-Off Tester

This guide provides a complete, professional procedure for using a diesel injector leak-off tester to compare return flow across all cylinders, which is the fastest way to isolate a worn or sticking injector without removing anything from the engine. It covers the tool's purpose, the main kit types and selection criteria, safe connection to the injector return circuit, a full step-by-step test, and a structured method for reading results with worked examples from real diagnostic jobs. Written for working mechanics and serious DIY owners who already understand common-rail and unit-injector systems, it finishes with the mistakes that ruin tests, care and calibration of the kit, and the point at which a specialist diesel shop should take over.