Not exactly. The diagnostic fault codes are set when the Engine Computer detects a problem, and it turns on the Check Engine light if that problem could adversely affect emissions. Very often a code won't set for these sensors, but if one does set, you'll know which circuit needs to be diagnosed. Reading the fault codes doesn't fix anything. It just tells you where to start looking.
Normally you need to plug in a scanner or simple fault code reader to read the codes. Many auto parts stores will do that for you for free, but you have to remember, they aren't mechanics. All they know is selling parts. Fault codes never say to replace parts or that they're bad. They only indicate the circuit or system that needs further diagnosis, or the unacceptable operating condition. When a sensor is referenced in a fault code, it is actually the cause of that code only about half of the time. You also have to look for wiring problems.
Chrysler is the exception to this. They have always made it real easy to read the fault codes yourself. You don't need a scanner or code reader, but all you'll get are three-digit numbers, so you'll need to look up their descriptions. Post those numbers here, or you can go to this page:
Thursday, September 25th, 2014 AT 10:15 PM