Error correction doesn’t insure truth. At least in communication, it insures that the final version matches the original version.

For AI, you wouldn’t be doing EC to make sure the AI was saying truth, you would be doing EC to ensure that the AI hasn’t drifted due to the 1% error rate.

Of course I have no idea how to actually do it - if it isn’t being done now, it is probably hard or impossible.

There's no fully general test for truth for an AI to run.

In some specific domains such tests exist — and the result is, generally, computers wildly outperforming humans. But I get the impression from using them that current LLMs didn't take full advantage of this during training.