BMW 1999-2005 M3 Service Manual page 1238

On-Board Diagnostics
11 of 11
Copyright © 2006 Robert Bentley, Inc. All rights reserved.
http://ebahn.bentleypublishers.com/BMW/3/E46/Repair%20Manuals/8...
check system integrity. On MS 43.0
cars, a more sophisticated DMTL
(Diagnostic Module - Leak Detection)
pump is used.
Drive cycle
The OBD II drive cycle is an important
concept in understanding OBD II
requirements. The purpose of the drive
cycle is to run all of the emission-
related on-board diagnostics over on a
broad range of driving conditions.
The drive cycle is considered
completed when all of the diagnostic
monitors have run their tests without
interruption. For a drive cycle to be
initiated, the vehicle must be started
cold and brought up to 160�F and at
least 40�F above its original starting
temperature.
Once the drive cycle is completed, the
system status or
inspection/maintenance (I/M) readiness
codes are set to "Yes."
System status codes will be set to "No"
in the following cases:
The battery or ECM is
disconnected.
The ECM's DTCs have been
erased after completion of repairs
and a drive cycle has not be
completed.
A scan tool can be used to determine if
on-board diagnosis is complete as well
as the status of the I/M codes. All
required tests must be completed
before the I/M readiness codes will be
set to "Yes".
Readiness codes
2/25/2009 11:22 PM