Fuel
Fuel Injector
Fuel injectors spray a fine, precisely metered mist of fuel into the intake or directly into the cylinder.
Free guide
Advertisement
Fuel delivery flow
Interactive — tap a partTap a part to see how it fits in the system.
What it does
- Delivers the exact fuel amount the ECU asks for
- Atomizes fuel for clean combustion
- Works at high pressure (direct injection can exceed 200 bar)
When it fails
- Misfire on a specific cylinder
- Rough idle
- Black smoke (leaking injector)
- P0201–P0204 circuit codes
How to diagnose
- Test injector resistance with a multimeter
- Swap injectors to see if the misfire moves
- Check fuel pressure and leak-down
Maintenance
- Use quality fuel and change the fuel filter on schedule
- Consider professional cleaning for high-mileage cars
Use the diagnosis order. When a part fails, confirm each hypothesis with measurements before replacing anything — codes and symptoms overlap.