I'm bringing soon my car to the dealer to fix a few things and don't want to get overcharged. First I got the CE light on with the code for the rear heated O2 sensor and second is when I start the car, there is a squeeling sound from under the hood, I don't now if it's the starter or the belts though. What rough approximation would you give for these 2 fixes?

 

The Rear Heated O2 sensor is more of a nuicance (sp?) than it is a performance killer. It is there to monitor the main cat so its replacement is not imperative. However, it makes that CEL go on which is pretty annoying. I think people have quoted everything from $90 to $160 or so for the O2 sensor itself with about a half hour labor. WARNING: The dealer may charge $300+ for this easy job you can do yourself.

As for the squealing. If it only happens at startup and for a second or two, take your car to a trusted mechanic to check the belt tension. If you just had new belts put on, you may have gotten past the "break in" period of the belts and need them readjusted. The mechanic who put them on should readjust them for free. Also, to pay a mechanic to check and adjust these shouldn't cost more than 30 mins of labor or so. I had all my belts and fuel filter replaced for less than $140 total just to give you an idea.

As with any problem, start with the simplest things first, when you rule those out, check out the more complicated things.

 

$400 a piece...
Thats how dealers do **** around here.
$400 for an estimate
$400 for them to tell you whats wrong
$400 for them to fix one thing

Stupid dealers... find a good private mechanic.

 

for the squealing noise - have your charging system checked out, it might be your alternator