BMW 5251 Service Manual page 961

OBD
On-Board Diagnostics
I
I
General
. . . . . . . . . . . . . . . . . . . . . . . . . . .
OBD-1
Diaqnostic Trouble Codes (DTCs)
. .
OBD-9
On-Board Diagnostics (OBD I!)
. . . . .
OBD-I
Malfunction Indicator Light (MIL)
. . . . . . . .
OBD-2
Scan tools and scan tool display.
. . . . . . . .
OBD-3
Diagnostic monitors
. . . . . . . . . . . . . . . . . .
OED-4
Drive cycle
. . . . . . . . . . . . . . . . . . . . . . . . .
OED-6
Readiness codes
. . . . . . . . . . . . . . . . . . . .
OBD-6
Diagnostic trouble codes (DTCs)
. . . . . . . .
OBD-7
-
Automatic transmission diagnostic
trouble codes
. . . . . . . . . . . . . . . . . . . . . . .
OBD-9
Engine diagnostic trouble
codes: M52 engine.
. . . . . . . . . . . . . . . . .
OED-13
Engine diagnostic trouble
codes: M54 engine.
. . . . . . . . . . . . . . . . .
OBD-17
Engine diagnostic trouble
codes: M62 engine.
. . . . . . . . . . . . . . . . .
OBD-24
This chapter outlines the fundamentals and equipment
requirements of On-Board Diagnostics I 1 (OBD 1 1 ) standards
as they apply to BMW vehicles. Also covered here is a listing
of BMW and OBD I 1 diagnostic trouble codes (DTCs).
ON-BOARD DIAGNOSTICS (QBD !I)
OBD II standards were developed by the SAE (Society of
Automotive Engineers) and CARB (California Air Resources
Board). OED I 1 is the second generation of on-board self-
diagnostic equipment requirements. These standards were
originally mandated for California vehicles. Since
1996
they
have been applied toall passengervehicles sold in the United
States.
On-board diagnostic capabilities are incorporated into the
hardware and soflwareof the enginecontrol module (ECM) to
monitor virtually every component that can affect vehicle
emissions. The OED I 1 system works to ensure that
emissions remain as clean as possible over the life of the
vehicle.
Each emission-influencing component is checked by a
diagnostic routine (called a monitor) to verify that it is
functioning properly. If a problem or malfunction is detected,
the diagnostic executive built into the OBD I 1 system
illuminates a malfunction indicator light (MIL) on the
instrument panel.
The OBD I 1 system also stores diagnostic trouble codes
(DTCs) about the detected malfunction in the ECM so that a
repair technician can accurately find and fix the problem.