An injector that does not respond correctly may have either an electrical-control problem or internal mechanical sticking.

The symptoms can overlap.

Electrical Command Comes First

Before assuming the nozzle needle is sticking, confirm that the injector receives the expected electrical command.

Check the relevant circuit according to system design.

Mechanical Sticking Can Exist With a Normal Circuit

If electrical behavior appears normal but injection remains inconsistent, internal mechanical movement may deserve investigation.

Possible causes can include:

• deposits;
• contamination;
• internal wear.

Dynamic Testing Provides Better Evidence

Useful comparisons may include:

Command Signal → Current Response → Cylinder Contribution → Bench Performance

If electrical input is normal but hydraulic response is abnormal, the diagnosis can move toward the injector itself.

Avoid Guessing From Fault Codes Alone

A cylinder-related fault code does not directly distinguish electrical failure from mechanical sticking.

Conclusion

Injector actuation involves both electronics and mechanics.

Separating those two layers helps prevent unnecessary wiring repairs or unnecessary injector replacement.