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Guys... had this '99 manual 6speed Vette for two weeks, seems to be running great but did the code check tonight to see how it works. Found these codes, not sure what they mean: Look forward to your thoughts. THANK YOU!
I think that they are on the level of communication related codes. The first thing I would do is CLEAR the codes, using the 'reset' button, then check them in a day or 2. If you don't see / experience anything 'unusual', AND the codes come back, check and clean all your grounding points.
If the car is running great, don't worry about these. There are all history codes, as indicated by the "H" suffix. They could be the result of a momentary glitch, particularly if the computer was recently flashed via the OBD-II port or if the battery was disconnected. If you are curious, you can look up most of them here and here.