Well, just hop in the Jeep and run down to Advance, AutoZone, Pep Boys, etc.
They'll check your codes for free, and even give you a list of probable causes.
And a note, a code is just telling you what part of the system is acting up, not always the part.
97 Sahara, 74 Renegade, 72 CJ5, 55 Willy's (the Beast) Boss 302, 6:34 gearing, Bose 901 speakers.
God I miss that Jeep. Forgot the kinda Jeep, 80 SX4.