## Common ground
All options refer to fuel injectors—devices that deliver fuel into an engine or combustion system in a controlled manner.
## Options at a glance
**8409.91 – Spark ignition engines**
- **Defining trait:** Designed exclusively for engines that ignite fuel with a spark (e.g., gasoline engines).
- **Typical examples:** Gasoline direct injection (GDI) injectors in passenger cars.
- **Best fit when:** The injector is used in petrol-powered vehicles or equipment.
**8409.99 – Compression ignition engines**
- **Defining trait:** Built specifically for diesel engines, where fuel ignites under high pressure.
- **Typical examples:** Diesel common-rail injectors in trucks or buses.
- **Best fit when:** The injector is used in diesel-powered vehicles or machinery.
**8413.91 – For liquid pumps**
- **Defining trait:** Used as part of a liquid pump system, not directly for engine combustion.
- **Typical examples:** Injectors in hydraulic or fuel transfer pump systems.
- **Best fit when:** The injector is part of a pumping mechanism, not an engine’s combustion process.
**8417.90 – Non-electric industrial furnaces**
- **Defining trait:** Designed for industrial heating systems using fuel, without electric actuation.
- **Typical examples:** Fuel injectors in oil-fired industrial boilers or kilns.
- **Best fit when:** The injector is used in large-scale non-vehicle combustion systems.
**8481.80 – Function as a valve**
- **Defining trait:** Primarily functions as a solenoid valve, with fuel injection being secondary.
- **Typical examples:** Gas injectors in vehicles that act like valves (e.g., shut-off or control valves).
- **Best fit when:** The device’s main role is flow control, not combustion delivery.
## Key differences
| Option | Primary Use Case | Ignition Type | Electric Actuation | Main System Type |
|-------|------------------|---------------|--------------------|------------------|
| 8409.91 | Spark ignition engines | Spark | Yes (usually) | Automotive engine |
| 8409.99 | Compression ignition engines | Compression | Yes (usually) | Diesel engine |
| 8413.91 | Liquid pumps | N/A | Varies | Pump systems |
| 8417.90 | Industrial furnaces | N/A | No (non-electric) | Heating systems |
| 8481.80 | Valve function | N/A | Yes | Flow control |
## How to choose
- Is it used in a gasoline engine? → 8409.91
- Is it used in a diesel engine? → 8409.99
- Is it part of a pump system (not combustion)? → 8413.91
- Is it for an industrial furnace, not a vehicle? → 8417.90
- Does it primarily act as a valve, not a fuel injector? → 8481.80
## Overlaps & pitfalls
- An injector in a diesel engine may also function as a valve (8481.80), but its primary purpose is combustion, so 8409.99 takes priority.
- Injectors for industrial furnaces (8417.90) might resemble engine injectors but are not for vehicles.
- If unclear whether it’s for an engine or a pump, focus on the system: combustion vs. fluid transfer.
- **No clear priority rule given**—choose based on the product’s MAIN function