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- -.
Fuel Injection
SIEMENS MIS 42.0 AND 43.0
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also illuminates
if an emissions-related fault is detected.
When faults arise, or
if the malfunction indicator lamp (MIL) is
illuminated, begin troubleshooting by connecting BMW ser-
vice tester
DISplus, MoDiC, GTI or equivalent scan tool. The
capabilities of OBD
II software has the potential to save hours
of diagnostic time and to help avoid incorrect component re-
placement and possible damage to system components.
CAUTION-
* The tests in this section may set fault codes (DTCs) in tlie
ECM and illuminate the MIL. After all testing is completed,
access and clear DTC fault
memory using an OBD I/ or
BMW compatible scan tool. See
OBD On-Board Diag-
nostics.
Only use a
dgital multimeter for electrical tests.
Relay positions can vary. Be sure to confirm
relayposi-
tion by identifying the wiring in the socket using the wir-
ing diagrams found in
ELE Electrical Wiring
Diagrams.
NOTE-
- OBD I1 fault memory. (including an illuminated MIL! can
only be reset using the special scan tool. Removing the
connector from the ECM or disconnecting the battery will
not erase the fault memory.
The BMW-dedicated 20-pin diagnostic
linlc connector
(DLC) is in the right rear of the engine compartment The
20-pin DLC is discontinued on models after
6/2000.
The 1 &pin OBD I1 diagnostic connector (arrow) is located
inside the car on the lower left dash panel.
The MS
42.0 and MS 43.0 systems manage the following
functions.
- Air:
Idle speed valve
Electronic throttle
Hot film mass air flow (MAF) sensor
Resonance-turbulence intake control
- Fuel:
* Fuel supply
Running losseslnon return
Fuel injection

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130-46
Fuel Injection
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also illuminates if an emissions-related fault is detected.
When faults arise, or
if the malfunction indicator lamp (MIL) is
illuminated, begin troubleshooting by connecting BMW ser-
vice tester
DISplus. MoDiC, GTI or equivalent scan tool. The
capabilities of
OED II software has the potential to save hours
of diagnostic time and to help avoid incorrect component re-
placement and possible damage to system components.
CA UTIOiU-
The tests in this section may set fault codes (DTCs) in the
ECM and illuminate the MIL. After ail testing is completed,
access and clear DTC fault
memory using an OED I/ or
BMW compatible scan tool. See OBD On-Board Diag-
nostics.
Only use a digital
multimeter for electrical tests.
Relay positions can vary. Be sure to confirm relay
posi-
. tion by identifying the wiring in the socket using the wir-
ing diagrams-found in ~~~~lectrical Wiring
Diagrams.
NOTE-
OED I1 fault memory (including an illuminated MIL) can
only be reset
using~the special scan tool. Removing the
connector from the ECM or disconnecting the battery will
not erase the fault
memory.
The BMW-dedicated 20-pin diagnostic link connector
(DLC) is in the right rear of the engine compartment.
The 16-pin OBD
I1 diagnostic connector (arrow) is located
inside the car on
the lower left dash panel.

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Fuel Injection
When system faults are detected, a diagnostic trouble code
(DTC) is stored in the engine control module (ECM). The MIL
also illuminates
if an emissions-related fault is detected.
When faults arise, or
if the malfunction indicator lamp (MIL) is
illuminated, begin troubleshooting by connecting BMW ser-
vice tester
DISplus, MoDiC, GTl or equivalent scan tool. The
capabilities of OBD
II software has the potential to save hours
of diagnostic time and to help avoid incorrect component re-
placement and possible damage to system components.
CA UTIOI\C
The tests in this section may set fault codes (DTCs) in the
ECM and illuminate the MIL. After all testing is completed,
access and clear DTC fault memory using an OBD
I1 or
BMW compatible scan tool. See OBD On-Board Diag-
nostics.
. Only use a digital multimeter for electrical tests.
Relay positions can vary. Be sure to confirm relay posi-
tion by identifying the wiring in the
socket using the wir-
ing diagrams found in ELE Electrical Wiring
Diaqrams.
NOTE-
= OBD I1 fault memory (including an illuminated MIL) can
only be reset using the special scan tool. Removing the
connector from the ECM or disconnecting the battery will
not erase the fault memory.
0 The BMW-dedicated 20-pin diagnostic link connector
(DLC) is in the right rear of the engine compartment. The
20-pin DLC was eliminated on models after
6/2000.
The 16-pin OBD I1 diagnostic connector (arrow) is located
inside the car on the lower left dash panel.

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Fuel Tank and Fuel Pump
Evaporative system troubleshooting
- Start by accessing diagnostic trouble codes (DTCs) using a
BMW or BMW compatible aftermarket scan tool.
For purposes of OBD
II emissions compliance, the DME
system sets a diagnostic trouble code (DTC) when it de-
tects a leak that is equal or larger than minimum
lealc
sensed by system.
Malfunction Indicator Light (MIL) is illuminated upon sec-
ond recurrence of fault. See OBD On-Board Diagnostics.
- When leak testing, observe following conditions to obtain
plausible results:
Fuel tank
'1, to 'I., full.
0 Vehicle parked for at least 2 hours to allow fuel to reach
room temperature.
Ideal fuel temperature is 10"- 20°C
(50"
- 68" F).
Do not refuel immediately before
lealc test.
- If a leak is detected, check the following areas:
* Fuel filter cap (leaking or off).
Fuel tank ventilation lines leaking at fuel
tank or activated
carbon canister.
i
Tank ventilation valve leaking (in engine compartment).
Fuel level
sensorlfuel pump cap leaking.
Evaporative system component replacement is covered later
in
th~s group in Fuel Tank and Fuel Lines.

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Warnings and cautions
Obse~e the following warnings and cautions when worlting
on the cooling system.
WARNING -
. At normal operating temperature the cooling system is
pressurized. Allow the system to cool as long as possible
before opening (a minimum of one hour), then release the
cap slowly to allow safe release ofpressure.
a Releasing the coolant system pressure lowers the cool-
ant boilingpoint and the coolant may boil suddenly. Use
1 heavy and wear eye and face protection to
guard against scalding.
Use extreme care when draining and disposing of en-
gine coolant. Coolant is poisonous and lethal to hu-
mans andpets. Pets are attracted to coolant because
of its sweet smell and taste. Seek medical attention im-
mediately if coolant is ingested.
CAUTIOG
Avoid adding cold water to the coolant while the engine is
hot or overheated. If it is necessary to add coolant to a
hol
system, do so only with the engine running and coolanl
pump turning.
To avoid excess silicate gel precipitation in the cooling
system and loss of cooling capacity, use BMW coolant
or equivalent low silicate antifreeze.
a If oil enters the cooling system, the radiator, expansion
tank and heating circuit must be flushed with cleaning
agent. BMW recommends removal of the radiator and
expansion
tank to flush.
When
worlcing on the cooling system, cover the alter-
nator to protect it against coolant drips.
Prior to disconnecting the battery, read the battery dis-
connection cautions given in
001 General Warnings
and Cautions.
Begin the diagnosis of cooling system problems with a thor-
ough visual inspection.
If no visual faults are found, it is rec-
ommend that the engine control module (ECM) fault memory
be checked for stored diagnostic trouble codes
(DTCs) using
BMW scan tool
DlSplus or equivalent.

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- .- -
Automatic Transmission
Electronics are used to control the operation of these auto-
matic transmissions. Steptronic transmission functions are
also programmed into the transmission control module
(TCM). The TCM monitors transmission operation for faults
and alerts the driver by illuminating the transmission fault indi-
cator on the instrument panel. Diagnostic trouble codes
(DTCs) stored in the TCM may be downloaded and interpret-
ed by trained technicians using special BMW diagnostic
equipment.
Some minor automatic transmission problems can be cor-
rected by changing the automatic transmission fluid (ATF)
and filter. Begin by checking ATF level and condition.
Checlc
to see if the fluid is dirty or has a burned odor indicating over-
heated fluid. The burned odor may be the results of burned
discs in theclutch paclts. The friction material from the burned
disc can clog valve body passages.
NOTE-
The E39 automatic transmission is not equipped with a dip-
stick.
Checking the ATF level must be done while monitoring
the ATF temperature with the engine idling. The
BMW dealer
is equipped with the special equipment to make this check.

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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
I1 (OBD 11) standards
as they apply to BMW vehicles. Also covered here is a listing
of BMW and OBD
I1 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 I1 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 I1 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 I1 system
illuminates a malfunction indicator light (MIL) on the
instrument panel.
The OBD
I1 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.

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OBD-3
On-Board
~iactnosticsl
Additional MIL information:
A fault code is stored within the ECM upon the first
occurrence of a fault in the system being checlted.
Two complete consecutive drive cycles with the iault
present illuminate the MIL. The exception to the two-fault
requirement is a catalyst-damaging fault, which illuminates
the MIL immediately.
If the second drive cycle was not complete and the fault
was not checked, the ECM counts the third drive cycle as
the next consecutive drive cycle. The MIL illuminates
if the
system is checked and the fault is still present.
Once the MIL is illuminated, it remains illuminated until the
vehicle completes three consecutive drive cycles without
detecting a fault.
0 An existing fault code is cleared from memory
automatically when the vehicle completes
40 consecutive
drive cycles without the fault being detected.
In order to automatically clear a catalyst-damaging fault from
memory, the condition underwhich the fault occurred must be
evaluated for 80 consecutive drive cycles without the fault
reoccurring.
A generic scan tool connected to the BMW data link
connector (DLC) or OBD
I1 plug can display diagnostic trouble
codes (DTCs), along with the conditions associated with the
illumination of the MIL. Using a more advanced or
BMW-
dedicated scan tool, additional proprietary information is
normally available.
Scan tool and scan tool display
The complexity of the OBD I1 system requires that all
diagnostics begin by connecting a scan tool to the vehicle.
Aftermarltet scan tools can be connected to either the 16-pin
OBD
I1 plug or the 20-pin BMW DLC in the engine
compartment
(ii installed). Data from the OBD II plug may be
limited, depending on scan tool and vehicle.
OBD
I1 standards reouire that the 16-oin OBD I1 oluo be
located within three
(3) feet of the driier and not're&ire any
tools to access.
Starting with June 2000 production, the 20-pin BMW DLC,
previously located in the engine compartment, was
discontinued. Diagnostic, coding and programming functions
are incorporated into the OBD
II plug, located under left side
of dashboard.
On cars built up to 06
/ 2000: when accessing emissions
related DTCs through the 16-pin OBD
I1 plug, malte sure the
BMW 20-oin DLC
caD is installed.