OBD-II(On-Board Diagnostics) codes are divided into four main sections, each prefixed with a letter. These four prefixes are as follow:
P = Powertrain B = Body C = Chassis U = Undefined
The number following the prefix tells you if the code is a generic OBD-II code or a manufacturer specific code. Generic codes start with a 0 (zero) while manufacturer specific codes start with a 1 (one).
The third number in the OBD-II code refers to any of the following sub-systems:
1 = Emission Management 2 = Injector Circuit 3 = Ignition/Misfire 4 = Emission Control 5 = Vehicle Speed and Idle Control 6 = Computer and Output Circuit 7 = Trans 8 = Trans 9 = SAE (reserved) 0 = SAE (reserved)
The last numbers in the code refer to a variable which is specific to the main problem.