Technical
Resistance and inductance: the electrical test that reveals the injector before the bench
September 22, 2026 · 2 min read
Measuring the injector coil takes minutes and helps discard parts with electrical defects. Learn how to perform the screening and what the limits of this test are.
Introduction
Many people take the injector straight to the bench. That’s the right way to evaluate hydraulic performance, but before that there’s a quick and cheap screening: measuring the injector’s coil (solenoid).
What each measurement shows
- Resistance: indicates an open circuit, a hard short, or resistance outside the expected range.
- Inductance: is more sensitive and helps identify partially shorted windings that resistance alone may not reveal.
Each injector model has its own range. Reference tables list resistance and inductance by part code and application (Iveco, Cummins, MWM, Sprinter, among others). Therefore, the first step is to identify the injector code and consult the correct range.
How to perform the screening
- Identify the injector code and application.
- Measure with the connector disconnected and on the correct instrument scale.
- Compare with the model’s reference range.
- Also compare injectors from the same set: values that differ greatly among them deserve attention.
- Record the values in the intake report.
Limits of the electrical test
An electrically perfect injector can fail hydraulically: wear, clogging, leakage, or excessive return only appear on the bench, with injection flow and return measurements. The electrical test serves to filter and save time, not to approve the part.
Tip: use the measurement as the first step of service. If it fails, you already have the reason to reject or recondition the injector before spending bench time.
Conclusion
Electrical screening plus bench testing form a complete process. You reduce diagnosis time, avoid rework, and deliver a documented result to the customer.
In diesel, measuring well is the first step to diagnosing right.
