Conditions for Clearing the MIL/DTC

WARNING: This page is about a different car, the 2002 GMC Safari and 2002 Chevrolet Astro. However, it is still accessible from the selected car via links, so may be relevant.

The PCM will turn the MIL OFF after three consecutive trips that the diagnostic has been run and passed.
The history DTC will clear after 40 consecutive warm-up cycles have occurred without a malfunction.
The DTC can be cleared by using the scan tool Clear DTC Information function.

DTC P1258 Diagnosis

Step	Action	Yes	No
1	Was the Diagnostic System Check for Engine Cooling performed?	Go to Step 2	Go to Diagnostic System Check - Engine Cooling
2	Check the engine cooling fan for proper operation. Does the engine cooling fan operative properly?	Go to Engine Overheating	Go to Symptoms - Engine Cooling