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Oxygen sensors only work when they are above approximately 650 degrees. Rather than waiting untill the exhaust heats up, the O2 sensor has a small heating element to bring it up to operating temp quickly. The O2 heater circuit code means the computer has detected a problem with the O2 sensor heater.
As fuel evaporates in the fuel tank, it builds pressure. This pressure has to be vented. Rather than venting it to the atmosphere, it goes to a charcoal filled canister which traps the fumes. When you drive there is a small valve which opens and allows the engine to draw these fumes into the intake and burn them, reducing evaporative emissions. The P0489 code means the computer detected a problem with the vent valve or the control circuit for it.
Hope this helps with the what. As for the why, you would be best off going to the dealer if it is still under warranty. If it is not under warranty (high mileage, etc.) try resetting the codes and see if they come back. If they do, you will have to have these systems (O2 sensor, Evaporative Emission system) checked out.
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