Got a check engine light, and was wondering how to check the codes, as well as clearing them. I see a little box bolted to the shock tower with that looks to be a diagnostic type thing. Is this it?

I have a feeling it's a Mass Air code because looking in the service records over the years, it seems that it popped up about 8 separate times. Sensor was replaced numerous times as well.

 

batauto.com has a great tutorial and code list but their domain is currently expired. I have it as a .pdf and will post it here but not too legible. Save to your computer and enlarge it.