naguirne

ran the manual check engine test that i found on here and found these codes.
0302 = Exhaust Gas Recirculation System Hi/Low Flow
1001 = Front Left Htd O2 sensor heater

great. now what? i looked at the more detailed explanation in the link given in the sticky and it really was detailed but it didn't help me understand what the problems are.

1. can anyone tell me what and where the EGR is so that I can actually check whether the valve is stuck or the passage is clogged like the sticky link suggests. (any other help/suggestions would be great too)
2. can anyone give any kind of explanation on what the second code is and what i should do about it.
3. is either of these codes serious? by serious i mean, detrimental to the car and if left unchecked will do damage.

needless to say, i am a newbie so please go easy on being overly technical from the start. but i do follow instructions well so feel free to go crazy with that.
thanks!