Clearing OBD II Diagnostic Trouble Codes (DTCs)

DTCs Can Be Cleared In Three Ways:
1 If the fault that caused the DTC to set has been corrected, the ECM counts the number of "warm up cycles" which have occurred since the last "test failed" was recorded by the ECM. In a "warm-up cycle" the engine temperature must reach at least 160°F (71°C) and must increase by at least 22°C (40°F) during the trip. When you have driven 40 warm-up cycles without a failure the DTC will automatically be cleared from memory.
2 DTCs can be cleared with a scan tool such as Intellegant Saab Tester (ISAT).
3 If the battery goes dead or the ECM loses +30 (constant) power for any reason, all DTC information, freeze frame data and inspection/maintenance readiness information will be lost after approximately 30 seconds.

IMPORTANT:
Do not clear codes unless directed to do so by the diagnostic procedure. When DTCs are cleared you also wipe out the freeze frame data which could help you diagnose the fault.