Monitoring Defect Code Memory

Defect code memory monitoring should be given first priority. If one or several detect codes are stored, It is advisable to immediately print out this data. Since it is often necessary during the testing procedure to cut the power supply or to disconnect the connector from the control unit, the content of the defect code memory will be unintentionally deleted as a consequence. On model year 1988, memory can store a maximum of 5 defect codes, whereby a detect code with higher priority can displace another defect code from memory. Defect codes are displayed in the order of detection. The following defects have higher storage priority:

• Air flow meter.
• Oxygen control.
• Engine temperature sensor.
• Idle switch.

As of model 1989, extended defect code memory stores all defect codes which are detected. When a defect code is stored and DME is not malfunctioning, substitute values can be active. The troubleshooting procedure should still, however, be carried out. Defect codes which influence the mixture are indicated CHECK ENGINE light in the instrument cluster. As a check, this light comes on in the time between ignition ON and engine start.