What OBD2 protocol is used on Holden Jackaroo 4jx1?

The Holden Jackaroo with the 4JX1 engine typically uses the ISO 9141-2 OBD-II protocol for diagnostic communication. This protocol is commonly found in older vehicles and allows for various engine and emission-related data to be accessed via an OBD-II scanner. However, it's always advisable to verify the specific model year, as protocol usage can vary.