The electronic control unit, or ECU, in your Saab controls a variety of vehicle systems. It also generates and stores error codes that are used to determine whether regular maintenance is required or whether there is a failure or malfunction in one of the Saab's critical vehicle systems (such as the fuel system, anti-lock braking system or the emissions system). Figuring out what is wrong with your vehicle, including whether your ECU is functioning properly, requires the use of an on-board diagnostic scanning tool, called an OBD tool. These tools are available from most auto parts stores.
Locate the open OBD port under the dash of your Saab, to the left of the fuse panel.
Plug the OBD plug into the OBD port on your Saab.
Turn the ignition key to the "II" position and wait for the ECU to provide you with a code on the scan tool's digital display.
Read your technical service manual (for the model and year of Saab you own) to determine what the numbered code refers to. If there is a problem with your ECU, this will also be reflected on your scan tool's digital readout. If the ECU is faulty, have it replaced by a professional mechanic.
