Mk4 Golf 2001 Transmission sensor error (P0715) - car fine after clearing, what now?

[lerlacher]

The wife called me today that her car (2001 Golf Mk4 1.6L 4-speed auto) was revving too high and didn't have any power when accelerating from a stop, pretty much the same as in these good old threads:

Automatic Transmission problem with the 1.6L Golf GL Mk4...
MK4 Golf 1.6 Automatic 4000rpm @ 100km/h

She said it started happening on Thursday. I drove the car on Saturday and didn't notice anything. Today (Monday) it was happening all day. She got the car home and after she turned it off the blowers ran for a good time to cool the engine down.

I went down to Jaycar and got their OBD-II Bluetooth Dongle and managed to read and clear ECU code P0715 (Input/Turbine Speed Sensor Circuit).

We went for a test drive and the car seems fine now - shifts as well as it ever did.

My conclusion from this is that there is a sporadic error (loose connection?) with one of the sensors, and the fault code was pending first but eventually got stored and the transmission was in constant limp mode from then on. Is that how it works?

Is it a safe bet that this is a purely electr(onic)al problem and the transmission is fine?

What do I do now? Just wait and see and take the car to the mechanic if the problem comes back?

Also, this is the Dongle I got: OBD-II Engine Code Reader with Bluetooth(R) Technology | Jaycar Electronics
I think it's ELM327-based.
Is there an app to read out the proprietary codes with this? Is it possible at all? I got "Torque Pro", it can only read the OBD-Code.