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All 698cc fortwos use an OBDII 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 and look similar to this:

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 ESP controller you will need access to a STAR.

The OBD port is located at the back of the shelf adjacent to the driver's door. The picture below shows location on an RHD car. For an LHD car, mirror the image.

There is a cover over the port which unclips from the top and swings down.

Plug in your code reader as follows and read out the codes from the car.

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:

Pin 1 SAM White / Grey
Pin 2 - -
Pin 3 ECU Blue (only on petrol engines)
Pin 4 Ground Brown
Pin 5 Ground Brown / Black
Pin 6 - -
Pin 7 ECU White
Pin 8 SAM Blue (switched live circuit 15)
Pin 9 ESP Yellow / Blue
Pin 10 - -
Pin 11 EPS Violet / Black
Pin 12 Restraint System Yellow / Red
Pin 13 - -
Pin 14 - -
Pin 15 - -
Pin 16 SAM Red / White (Permanent Live)

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