DTC Numbering

All OBD II Diagnostic Trouble Codes displayed by the scan tool are five characters long. They all begin with a letter of the alphabet followed by four numbers.

The first character, a letter of the alphabet, indicates which system stored the fault:

• P for Powertrain

• B for Body

• C for Chassis

• U for a problem in the vehicle’s onboard communications network

Most emissions-related DTCs you’ll see will begin with the letter P, although it is possible for a component in one of the other systems (B-Body, C-Chassis, or U-Network Communications) to store an emissions related DTC.