# Bosch 4021

> All equivalents for the Bosch 4021 spark plug: compatible references, technical specifications and where to buy.

## Technical information

- **Thread:** 14 mm
- **Reach:** 18.5–21.5 mm
- **Heat range:** Very hot
- **Resistor:** yes
- **Seat:** Flat (gasket)
- **Torque:** fonte 25–35 N·m · alu 25–30 N·m — ou 180°–240° (½–⅔ tour)

## 11 equivalents

- [Bosch WR9DP4](https://www.thesparktwin.com/en/bosch/wr9dp4/)
- [Bosch WR9LP4](https://www.thesparktwin.com/en/bosch/wr9lp4/)
- [Bosch WR9DPX4](https://www.thesparktwin.com/en/bosch/wr9dpx4/)
- [Autolite AP66](https://www.thesparktwin.com/en/autolite/ap66/)
- [Splitfire PP006F](https://www.thesparktwin.com/en/splitfire/pp006f/)
- [Bosch 4120](https://www.thesparktwin.com/en/bosch/4120/)
- [Bosch 4121](https://www.thesparktwin.com/en/bosch/4121/)
- [Bosch 4137](https://www.thesparktwin.com/en/bosch/4137/)
- [Bosch 4237](https://www.thesparktwin.com/en/bosch/4237/)
- [Champion 3405](https://www.thesparktwin.com/en/champion/3405/)
- [Denso 3230](https://www.thesparktwin.com/en/denso/3230/)

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*Source : [Bosch 4021](https://www.thesparktwin.com/en/bosch/4021/) — TheSparkTwin*