Loading ...
Loading ...
Loading ...
4
GENERAL INFORMATION
On-Board-Diagnostics (OBD) II
The first generation of On-Board Diagnostic (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 OBD I system increased, a new generation of On-Board
Diagnostics 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:
•
Whether the Malfunction Indicator Light (MIL) is commanded ‘on’ or ‘off’;
• Which, if any, Diagnostic Trouble Codes (DTCs) are stored;
• Readiness Monitor Status.
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 the control system which sets the code. The other
four characters, all numbers, provide additional information on
where the DTC originated and the operating conditions that caused
it to set. Here is an example to illustrate the structure of the digits:
Loading ...
Loading ...
Loading ...