Next steps using parking sensors?

[guyskin]

This 2018 Kia Stonic is mine. 'Check system' was the notification that popped up on my dashboard a few weeks ago.
The reverse camera is fully functional.
After using the screwdriver approach to verify each sensor, I still received the error message, so I'm not sure it's the sensors. I even bought replacement sensors and attempted using them in lieu of the originals, but they didn't work either.

Then what should I verify?
I rely more on the camera than the sensors, and I'm old enough to have driven many cars without them, so I don't want to spend a lot of money on this.
It appears that many Kia owners are experiencing this problem and have not found a definitive solution.
Thank you!

[badgx]

It will not pass the mot if the warning notice is visible, therefore take it to the dealer for a full diagnosis. I understand that you would rather not spend money on the automobile, but each time you purchase a component and it doesn't function, it's money wasted! If you're fortunate, your neighbourhood repair shop may offer a diagnostic kit that can identify the solution for a little less money, or you may just spend an hour of effort and get the answer.

[guyskin]

Well, I suppose I'll give my neighbourhood repair shop a ride. I had no idea if it would fail the MOT or not.
I am grateful.

[Screwdriver_1]

Using an OBD reader, check for the presence of fault codes.

[Howard_silver]

On eBay, you can get an ELM327 OBD2 Bluetooth Adapter for next to nothing, and the Torque app, which can read it, is available for free on Android.

[guyskin]

I will have a look. Thank you.