After analyzing dozens of actual repairs, here are the root causes of DF417, ranked by frequency:

The injector on cylinder 4 fails internally – typically a shorted or open solenoid coil. Injector resistance should be around 0.2–0.5 ohms. An open circuit or extremely high resistance confirms a bad injector.

If your vehicle has stored code DF417, you will likely notice:

If you are restoring a vehicle with a Renault DF417, be aware of the following typical failure points: