iCarsoft MB II - 2 General Information; O N -Board Diagnostics (Obd) II; Diagnostic Trouble Codes (Dtcs)

iCarsoft English User’s Manual
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2. General Information
2.1 On-Board Diagnostics (OBD) II
The first generation of On-Board Diagnostics (called OBD I) was developed by
the California Air Resources Board (ARB) and implemented in 1988 to monitor
some of the emission control components on vehicles. As technology evolved
and the desire to improve the On-Board Diagnostic system increased, a new
generation of On-Board Diagnostic system was developed. This second
generation of On-Board Diagnostic regulations is called “OBD II”.
The OBD II system is designed to monitor emission control systems and key
engine components by performing either continuous or periodic tests of
specific components and vehicle conditions. When a problem is detected, the
OBD II system turns on a warning lamp (MIL) on the vehicle instrument panel
to alert the driver typically by the phrase of “Check Engine” or “Service Engine
Soon”. The system will also store important information about the detected
malfunction so that a technician can accurately find and fix the problem. Here
below follow three pieces of such valuable information:
1) Whether the Malfunction Indicator Light (MIL) is commanded ‘on’ or ‘off’;
2) Which, if any, Diagnostic Trouble Codes (DTCs) are stored;
3) Readiness Monitor status.
2.2 Diagnostic Trouble Codes (DTCs)
OBD II Diagnostic Trouble Codes are codes that are stored by the on-board
computer diagnostic system in response to a problem found in the vehicle.
These codes identify a particular problem area and are intended to provide you
with a guide as to where a fault might be occurring within a vehicle. OBD II
Diagnostic Trouble Codes consist of a five-digit alphanumeric code. The first
character, a letter, identifies which control system sets the code. The second
character, a number, 0-3; other three characters, a hex character, 0-9 or A-F
provide additional information on where the DTC originated and the operating
conditions that caused it to set. Here below is an example to illustrate the
structure of the digits: