I suspect some tools are capable. Like resetting the CEL. You have to check the tool.

The OBD Fusion App $5.00 and Toyota Lexus Scion PID pack $10, should do it.

 

Of course, I spoke too soon. So there's still intermittent pinging, but definitely not as frequent and not as loud. Still looking for a window to get the O2 sensor done.
The mystery continues...

 

It's not uncommon that all apps dont do everything. You'd have cell on if the sensors were even remotely incapable of reporting data. I don't think that is your problem.

Also, don't leave seafoam in the crankcase too long. Read the label for max duration.

Are you absolutely certain the sound is detonation?

 

Before you get it done can you just check to see if it's still connected. Both of them. I am not asking you to change them. If they are still on there but disconnected. Your afr sensors are not reporting voltage, your post cats ones are, and they are displaying the correct fluctuations, 0.1v - 0.95v usually.

 

So I finally got back into another shop (a legit Toyota specialist), they hooked up their OBDII and found that the O2 sensors are all working properly. Apparently, my app wasn't reading properly for sensor 1. He took it for a spin and believes the pinging is related to carbon buildup.
He said it was probably just a coincidence that it started to happen after the spark plug change. Although, I'm wondering if the OEM sparkplugs that are in it now (Denso) run hotter than the NGKs that were in it before the spark plug change? Could a temperature difference cause pinging? Regardless, I'm inclined to agree that it's a carbon issue.

 

Did you ever find out what was causing your pinging?