Stored DTC

[NOV87]

Do stored codes clear after a few drive cycles? Something as simple as when an ignition coil left unplugged and engine started, MIL popped up. The engine was shut off and the MIL cleared successfully. But, if one scans for DTC's, the same code is displayed as "stored". No rough idle, the engine is whisper quiet. Nothing abnormal otherwise...

 

[NOV87]

I think, I've found an answer to that from
bar.ca.gov/Industry/PDTC :

What are Permanent Diagnostic Trouble Codes?​

Permanent Diagnostic Trouble Codes (PDTCs) are very similar to regular Diagnostic Trouble Codes (DTCs). However, unlike regular DTCs, they cannot be reset by disconnecting the vehicle’s battery or cleared using an On-Board Diagnostic (OBD) scan tool. The only way to clear a PDTC is to fix the underlying problem with the vehicle that originally caused the PDTC and its corresponding DTC to set, and then allow the vehicle sufficient drive time to re-run the monitor that identified the problem in the first place. When the monitor runs without identifying a problem, the PDTC will clear itself.

 

[csuder99]

Yes. The "drive cycle" part can be a little tricky depending on where/how the vehicle is driven. Typically it takes three trouble-free drive cycles to clear the MIL so that should clear the stored code. In some cases it only takes one drive cycle after clearing the MIL with a tool.
In any case if the problem is fixed the stored code will disappear sooner or later. Just went through this with my Jeep twice, once for a stuck open thermostat and then a defective coil pack.