All 599cc fortwos use an OBD interface to create a link between the car's systems and the user. You can buy generic code readers online with varying costs for various functionality. These units will read information from the engine control unit but the ultimate tool (that smart dealers use) is a STAR machine which can read all smart-specific codes as well. However, these are far out of the price range of individual owners. With generic code readers you can do basic functions such as reading fault codes and clearing them. However, to fix faults with the airbag system and TRUST controller you will need access to a STAR.

The OBD port is located on the front of the ZEE unit within the left side footwell. You may or may not have the fabric panel as shown. If you do, you will see a rectangular cut-out where the OBD socket is located.

Take your code reader and insert the connector as shown.

For information, the wiring of the OBD socket and functionality of the pins are detailed below. There are individual connections to each of the main systems:

• ECU (MEG or EDG)
• Restraint system
• Electronic power steering (optional extra)
• Electronic stability programme (traction control)
• SAM control unit

If you wanted to wire in anything directly to the port then the wiring colours into the back of the port are as follows: