My link to the specific codes doesn't work anymore but I'm sure a quick google search will get you what you need.

Here is a breakdown of what each digit of the code means:

First Character - System

The first character identifies identifies the system related to the trouble code.

* P = Powertrain
* B = Body
* C = Chassis
* U = Undefined

Second Digit - Code Type

The second digit identifies whether the code is a generic code (same on all OBD-II equpped vehicles), or a manufacturer specific code.

* 0 = Generic (this is the digit zero -- not the letter "O")
* 1 = Enhanced (manufacturer specific)

Third Digit - Sub-System

The third digit denotes the type of sub-system that pertains to the code

* 1 = Emission Management (Fuel or Air)
* 2 = Injector Circuit (Fuel or Air)
* 3 = Ignition or Misfire
* 4 = Emission Control
* 5 = Vehicle Speed & Idle Control
* 6 = Computer & Output Circuit
* 7 = Transmission
* 8 = Transmission
* 9 = SAE Reserved
* 0 = SAE Reserved

Fourth and Fifth Digits

These digits, along with the others, are variable, and relate to a particular problem

For example,a P0171 code means P0171 - System Too Lean (Bank 1)