Diagnostic Trouble Codes for OBD II
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.
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
4th & 5th digit - two place fault code 0-99
Types of DTC’s
There are two categories of DTC’s that apply to OBD II. They are listed below with Type A being the more severe.
1. Emissions related.
2. Requests illumination of the MIL after one failed driving cycle.
3. Stores a freeze frame DTC after one failed driving cycle.
I. Emissions related.
2. Sets a Pending Trouble Code after one failed driving cycle.
3. Clears a Pending Trouble Code after one successful driving cycle.
4. Turns on the MIL after two consecutive failed driving cycles.
Stores a freeze frame after two consecutive failed driving cycles.