# HS code 8409.91: Suitable for use solely or principally with spark-ignition internal combustion piston engines

> HS code 8409.91 covers suitable for use solely or principally with spark-ignition internal combustion piston engines, other than those classified in 8409.99. It sits in heading 84.09 (parts suitable for use solely or principally with the engines of heading 84.07 or 84.08) in chapter 84 (nuclear reactors, boilers, machinery and mechanical appliances; parts thereof). Other goods of heading 84.09 are classified under 8409.10 (for aircraft engines) and 8409.99 (other, other). National tariff lines under 8409.91 are live on border.bot for the United States (11 lines, also used by 1 other country).

Source: https://border.bot/hs-codes/840991
Last updated: 11 October 2026

[HS codes](https://border.bot/hs-codes) / [Chapter 84](https://border.bot/hs-codes/84) / [84.09](https://border.bot/hs-codes/8409) / [8409.91](https://border.bot/hs-codes/840991)

## Key facts

- HS code: 8409.91
- Covers: Suitable for use solely or principally with spark-ignition internal combustion piston engines
- Heading: [84.09: Parts suitable for use solely or principally with the engines of heading 84.07 or 84.08](https://border.bot/hs-codes/8409)
- Chapter: [84: Nuclear reactors, boilers, machinery and mechanical appliances; parts thereof](https://border.bot/hs-codes/84)
- Edition: HS2022
- Duty in the United States: [See its 11 lines](https://border.bot/countries/united-states/hs-codes/840991)

## What this code covers

HS code 8409.91 covers suitable for use solely or principally with spark-ignition internal combustion piston engines, other than those classified in 8409.99.

The legal text of the subheading is “Other: Suitable for use solely or principally with spark-ignition internal combustion piston engines”, read under “Other”, in HS2022.

## What it doesn’t cover

Other goods of heading 84.09 are classified under 8409.10 (for aircraft engines) and 8409.99 (other, other).

- [8409.10](https://border.bot/hs-codes/840910) For aircraft engines
- [8409.99](https://border.bot/hs-codes/840999) Other: Other

## How it is structured

8409.91 is a six-digit subheading. Its first two digits, 84, are the chapter; the first four, 8409, are heading 84.09; the last two, 91, identify the subheading within the heading.

Countries add their own digits after these six for their national tariff lines.

- Chapter 84: Nuclear reactors, boilers, machinery and mechanical appliances; parts thereof
- Heading 84.09: Parts suitable for use solely or principally with the engines of heading 84.07 or 84.08
- Within the heading: Other
- Subheading 8409.91: Suitable for use solely or principally with spark-ignition internal combustion piston engines

## In other countries

National tariff lines under 8409.91 are live on border.bot for the United States (11 lines, also used by 1 other country).

- [United States](https://border.bot/countries/united-states/hs-codes/840991): 11 lines, used by 1 other country

- Previous subheading: [8409.10](https://border.bot/hs-codes/840910) For aircraft engines
- Next subheading: [8409.99](https://border.bot/hs-codes/840999) Other: Other

## Frequently asked questions

### What does HS code 8409.91 cover?

HS code 8409.91 covers suitable for use solely or principally with spark-ignition internal combustion piston engines, other than those classified in 8409.99.

### Which heading and chapter is HS code 8409.91 in?

HS code 8409.91 is in heading 84.09 (parts suitable for use solely or principally with the engines of heading 84.07 or 84.08) in chapter 84 (nuclear reactors, boilers, machinery and mechanical appliances; parts thereof).

### Where are goods of heading 84.09 classified when 8409.91 doesn’t fit?

Other goods of heading 84.09 are classified under 8409.10 (for aircraft engines) and 8409.99 (other, other).

### Which countries’ tariffs list national lines under HS code 8409.91?

National tariff lines under 8409.91 are live on border.bot for the United States (11 lines, also used by 1 other country).

## Sources and updates

The Harmonized System legal text comes from border.bot release 2 (edition HS 2022), imported from a file, and has been live since 11 October 2026.

This page was last updated on 11 October 2026.

Guidance from published tariff data, not a binding ruling. For a decision customs must follow, apply to the destination’s customs authority for a binding tariff ruling.

Machine-readable: https://border.bot/hs-codes/840991.json