Toyota Repair: check engine & humming sound..., power steering rack, mass air flow

Question
Hello ted,

i had this "check" alarm on my 1999 toyota avalon dashboard, i brought the car to one shop here in Abu Dhabi, UAE, for diagnosis and they got the following fault:
1. mass air flow circuit malfunction - P0100
2. intake air temperature circuit - P0110
3. O2 sensor circuit malfunction
4. evaporation ventilation control malfunction -   P0446

also this humming or whining sound when i'm accelerating @ about 1200 rpm - 1400 rpm the sound is coming but more than this given RPM the sound is gone, i tried to switch off the a/c but the sound is still there, where do you think the sound is coming from? please help me, i really hate to have this things in my car, thanks...

best regards,
albert  

Answer
For the time being disregard all but the O2 sensore and the evap system PO446.
For the O2 sensor code find out which sensor is malfunctioning I need the DTC to help here, there are two of them on this engine in front of the catalityc converter, it's either bank one or bank two, whichever it is replace that one, by the way bank one is located next to the firewall.
The 446 code may have been triggered by a loose or missing fuel cap, make sure the cap is on tight, then open the hood and remove the negative battery terminal and wait ten seconds and reconnect it this will clear the computer from all the codes.
Not sure about the noise, it could be a power steering leak, check the p/s reservoir and make sure the fluid level is up, if not there may be a leak at either the power steering pump or the power steering rack seals.