I found this while looking for a b0800 code thought it might be handy:
Anatomy of OBDII (DTC) Diagnostic Trouble Code
A DTC is made up of 5 digits. The figure below demonstrates the composition of a DTC. With this information it is easier to trouble shoot DTC without knowing the description of the code.
Example P0101
1st digit B-Body, C-Chassis, P-Powertrain, U-Network
2nd digit 0-SAE, 1 mfg
3rd digit 1 Air & Fuel Metering
2 Air & Fuel Metering (Injector Circuit)
3 Ignition System or Misfire
4 Auxiliary Emissions Controls
5 Vehicle Speed Controls And Idle Control System
6 Computer Output Circuit
7 Transmission
8 Transmission
4th & 5th digit - two place fault code 0-99