Dead Hybrid Battery Maybe?

could be corrosion

 

The P3006 is the car's built-in battery control ECU telling you that it has seen excessive charging/discharging voltage variation between the battery modules, and has seen it on two separate trips. If you reset the codes, the two-trip detection rule means you won't see the codes again until the excess voltage swings have again been logged by the computer on two separate trips.

There is a procedure in the repair manual for observing that. It doesn't involve just writing down a bunch of voltage readings at a point in time; it involves watching Techstream's MAX V and MIN V together while repeating an engine-running/engine-stopped stall test in reverse over a period of more than twenty minutes.

So when the mechanic is telling you nothing's wrong with the battery, he's telling you that the clear P3006 reported by the battery ECU is a mistake. I'm not going to say that's impossible, or the computer is infallible or anything, but if he's going with the story that it is mistaken, he shouldn't just stop there. He should be continuing the story with how he thinks the ECU got to that wrong conclusion, what his evidence is for that explanation, and what he thinks ought to be done to fix it.

My 2001 manual doesn't have P0443 in it; that looks like an evaporative-emissions related code they might have added for 2002. It probably has the same kind of two-trip detection rule that the battery code has, so again, if you clear it, you don't see it again until the ECM has detected the problem again and confirmed it is there on two different trips.

It isn't related to the other codes you had before; it is just a separate issue the car has developed more recently.