Alldata is a good site, but usually I just call the dealership and talk to service and they can tell you exactly what the code is. Plus with the computer controlled cars these days its 95 percent of the time a sensor..........02, crank position, cam position, vaccuum leak in gas tank return system, etc.
Personally, I think they put all these damn sensors on the cars and charge $150.00 for them because the engines are running a long time these days, so if the sensors go out you need to have engine work done. So, with a $150.00 sensor plus $195.00 for diagnostics (ie OBDII reader) thats $345.00 for a sensor that the engine runs fine without. A damn crank sensor, come on, nothin' a good timing light cant find out. But then again the computer adjusts for any discrepancies................... :beer: