If you live far from an auto store and want ability to check your own codes here is something nice.

It checks codes and runs diagnostics. You have to pair it with iPhones dashcommand or androids Torque.

http://pages.ebay.com/link/?nav=item...d=111177868910

Auto ELM327 V1.5 Interface Bluetooth OBD 2 OBD-II Car Diagnostic Auto Scanner US

 

Maybe a pulley, water pump, or timing chain tensioner? I had a noise I had to track down as well and it ended up being my water pump. Here is what I did:

Removed both belts spun each pulley.
Kept the serpentine belt on and started the car.
Started the car with no belts (don't run too long). Every light will turn on

If the noise is still there it could be the water pump, timing chain tensioner, or broken guide rail. You can replace the water pump and tensioner by removing the two small access ports depending on the year. Otherwise you'll have to remove the entire front cover. I replaced my primary chain, water pump, and all the guide rails and car runs perfect now.

 

Figured out the noise problem! Solved! I'm very excited as I just fixed that annoying rattling sound from my engine. I couldn't get a good oil read with the dip stick due to many issues. But figured out that my oil was leaking and my engine was running dry! Scary stuff. But I just added 3 quarts of 10w-30 full synthetic oil to engine and drive it for 5 mins and noise completely went away! I think my problem was that the oil coolant gasket ring is worn out? Not too positive on this yet as I haven't had a day off from work yet to change oil and filter. I order new gasket and probly will get a bigger filter and see if the leak goes away. Now it's time to do the spark plugs and belts now. Thanks for everyone's input and opinions it helped a lot. And hopefully this will help anyone that has a leak too