When should diagnostic trouble codes (DTCs) be cleared?

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DTCs should be cleared only when the service information directs you to do so, or after you have completed a repair and want to verify that the fault does not return during operation. Clearing codes resets the diagnostic memory, which is useful for starting fresh after a repair or when the manufacturer specifies a reset as part of the procedure. If you clear codes too early or without guidance, you may erase evidence of the original fault, making it harder to diagnose or confirm that the repair actually addressed the issue. Battery changes can cause codes to appear or disappear, but they aren’t a blanket reason to clear DTCs unless the service info specifically instructs it. Clearing codes after every test run, or only after an engine rebuild, isn’t a standard practice unless the manufacturer’s procedure requires it. Focus on following the service information and clearing codes only when that guidance or the repair verification process calls for it.