Clearing Diagnostic Trouble Codes

When the ECM sets a code, the "Service Engine Soon" light will come "ON" and a code will be stored in memory. If the problem is intermittent, the light will go out after 10 seconds, when the fault goes away. However, the code will stay in the ECM memory for 50 starts, or until the battery voltage to the ECM is removed. Removing battery voltage for 30 seconds will clear all stored codes.

Codes should be cleared after repairs have been completed. Also, most diagnostic charts will tell you to clear the codes before using the chart. This allows the ECM to set the code while going through the chart, which will help to find the cause of the problem more quickly.

NOTICE To prevent ECM damage, the key must be "OFF," when disconnecting or reconnecting power to ECM (for example battery cable, ECM pigtail, "ECM-IGN" fuse,jumper cables, etc.).