100-4
ENGINE-GENERAL
'
TEMP
PRECAT
POST
CAT
OXYGENSENSOR
HEATING
#
.
THROTTLE
POSITION
FUEL
INJECTOR
CONTROL
(SEQUENTIAL)
OPERATING
POWER
00
CAMSHAFT
POSITION
SENSOR
ECM
I
MAIN
GROUND
RELAY
J_
-
AC
COMPRESSOR
RELAY
CONTROL
TERMINAL
15
MEMORY
POWER
FUEL
PUMP
RELAY
CONTROL
AUX
GROUND
P
CRANKSHAFT
POSITION
dESENSOR
INTAKE
AIR
ENGINE
COOLANT
TEMP
FUEL
TANK
PRESSURE
SENSOR
S-EML
S-MSR
ASC
S-ASC
VEHICLE
SPEED
LOW
FUEL
LEVEL
A/C
SWITCH
ON
(AC)
E36
IHKA
COMPRESSOR"ON"
SIGNAL
(KO)
INDIVIDUAL
SERIAL
NUMBER
MS41
.1
SECONDARY
AIR
1NJECTION
AIR
PUMP®
RELAY
CONTROL
IDLE
CONTROL
VALVE
'M
FUEL
INJECTION
(TI)
ENGINE
SPEED
(TD)
Fig
.
5
.
Siemens
MS
41
.1
OBD
II
engine
management
systemusedon
1996
and
later
M52
engines
.
GENERAL
IGNITION
COILS
CONTROL
L
r"Q
if~
CIYVFIYC
CHE
AMP
CONTROL
ENGINE
THROTTLE
POSITION
6
ECM
RELAY
CONTROL
ASC
THROTTLE
..
:
.
.
..
-11
1Q\\\
POTENTIOMETER
POWER
CAN
TCM
II
SCAN
(DES
;
ER
DIAGNOSIS
OBD
II
I
II
GENERIC
SCANTOOL
0012596
100-6
ENGINE-GENERAL
Cylinder
compression,
checking
A
compression
tester
is
needed
to
make
a
compression
test
.
To
obtain
accurate
test
results,
the
battery
and
starter
must
be
capable
of
cranking
the
engine
at
250-300
rpm,
and
theen-
gine
should
be
at
normal
operating
temperature
.
Use
com-
pressed
air
to
clean
aroundthe
spark
plugs
before
removal
.
1
.
Disable
the
ignítion
system
by
removing
the
engine
management
system
main
relay
and
the
fuel
pump
re-
¡ay
.
See
Fig
.
6
.
WARNING
-
The
ignítion
system
produces
high
voltages
that
canbe
fatal
.
Avoid
contact
with
exposed
termínals
and
useextreme
caution
when
working
on
acar
wíth
the
ignítion
switched
on
or
the
engine
running
.
Fuel
DM
E
pump
main
re
ay
rel
ay
o
oa
ooa
.,
o00
oao
Fig
.
6
.
Engine
management
relays
in
power
distribution
box
inleft
rear
of
engine
compartment
.
CAUTION-
"
On
OBD
11
cars,
making
a
compression
test
may
causea
faultto
set
in
the
ECM
and
may
also
il-
luminate
the
Check
Engine
light
.
The
light
can
only
be
tumed
out
using
special
scan
tool
equip-
ment,using
eíther
the
BMW
specialservíce
tool
or
using
a
"generic"
OBD
11
scan
tool
.
Discon-
necting
the
battery
will
not
erase
the
fault
mem-
orynor
turn
outthe
light
.
0013034,
0012630
Fig
.
7
.
Remove
spark
plug
wires
from
spark
plugs
on
4-cylinder
en-
gine
using
special
tool
.
Tool
is
stored
under
cover
at
rear
of
cylinder
head
(arrow)
.
Fig
.
8
.
Remove
engine
cover
on
6-cylinder
engine
byprying
off
nut
covers
and
removing
nuts
(A)
.
Be
careful
not
to
let
rubber
in-
sulators
fall
off
as
cover
is
removed
(arrows)
.
4
.
On
6-cylinder
engines,
disconnect
the
harness
connec-
tors
from
the
ignítion
coils
by
lifting
the
retaining
clip
.
Remove
the
coil
mounting
nuts
andremove
the
six
coils
.
See
Fig
.
9
.
Remove
the
sparkplugs
.
"
Failure
to
remove
the
main
relay
or
attempting
to
disable
the
ignítion
system
by
other
methods
may
resultin
damage
to
the
engine
control
module
.
NOTE-
Used
sparkplugs
should
be
reinstalled
in
the
same
cyl-
2
.
On
4-cylinder
engine
:
Remove
plastic
engine
cover
from
inder
fromwhich
they
were
removed
.
top
of
cylinder
head
.
Disconnect
spark
plug
wires
and
re-
move
spark
plugs
.
See
Fig
.
7
.
5
.
Insta¡¡
the
compression
gauge
in
the
first
cylinder's
3
.
On
6-cylinder
engine
:
Remove
top
engine
coverby
pry-
spark
plug
hole,
tight
enough
to
form
a
good
seal
.
ing
off
nut
covers
and
removing
mounting
nuts
.
See
Fig
.
8
.
MECHANICAL
TROUBLESHOOTING
100-
1
0
ENGINE-GENERAL
Table
d
.
OBD
I
Fault
(Blink)
Codes
(continued)
(1992-1995
modeis
only)
Graphic
representation
of
flashing
Check
Engine
light
fault
code
:
1221
-
;
5
Seconds
.
;--~
2
.5
r
----------------
Check
Engine
light
on
Fault
code
and
meaning
Corrective
action
Check
Engine
light
off
Code
1243
:
Crankshaft
position
sensor
(DME
3
.3
.1
only)
Test
crankshaft
position/rpm
sensor
and
wiring
from
sensor
lo
DME
control
module
.
Repair
Group
120
Code
1244
:
Camshaft
position
sensor
(DME
3
.3
.1
only)
Test
camshaft
position
sensor
and
wiring
fromsensor
to
DME
con-
trol
module
.
Repair
Group
130
Code
1245
:
Electronic
transmission
control
intervention
(DME
3
.3
.1
Check
wiring
between
DME
control
module
and
auto
.
transmission
only)
control
module
Code
1247
:
Ignition
secondary
monitor
(DME
3
.3
.1
only)
Check
secondary
voltage
lo
ignition
coils
.
Check
wiringat
ignition
coils
.
Repair
Group
120
Code
1251
:
Fuel
injector
#1
(DME
3
.113
.3
.1
only)
1
Test
injector
operation/signal
lo
injector
.
Repair
group130
Code
1252
:
Fuel
injector
#2
(DME
3
.113
.3
.1
only)
Test
injector
operation/signal
lo
injector
.
Repair
group130
Code
1253
:
Fuel
injector
#3
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
to
injector
.
Repair
group130
Code
1254
:
Fuel
injector
#4
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
to
injector
.
Repair
group
130
Code
1255
:
Fuel
injector
#5
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
to
injector
.
Repair
group130
Code
1256
:
Fuel
injector
#6
(DME
3
.1/3
.3
.1
only)
Test
injector
operation/signal
lo
injector
.
Repair
group130
Code
1261
:
Fuel
pump
control
Test
fuel
pump
relay
and
fuel
pump
circuit
.
Repairgroup
160
Code
1262
:
Idle
speed
control
Test
idleair
controlvalve
and
signalto
valve
.
Repair
Group
130
Code
1263
:
Fuel
tank
evaporative
(EVAP)
system
Test
EVAP
purge
valve
.
Repair
Group
160
Code
1264
:
Oxygen
sensor
heater
1
Test
oxygen
sensorheater
and
heater
relay
.
Repair
group
130
Code
1265
:
Check
engine
lamp
(DME
3
.3.1
only)
1
Test
for
faulty
bulb
or
wiring
.
Electrical
Wiring
Diagrams
Code
1266
:
VANOS
(DME
3
.3
.1
only)
1
Test
VANOS
solenoid
.
Check
for
signal
to
VANOS
solenoid
.
Code
1267
:
Air
pump
relay
control
(DME
3
.3
.1
only)
Test
air
pump
relay
and
wiring
(where
applicable)
Electrical
Wiring
Diagrams
Code
1271
:
Ignition
coil
#1
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
toignitioncoil
.
Repair
Group
120
Code
1272
:
Ignition
coil
#2
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1273
:
Ignition
coil
#3
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1274
:
Ignítion
coil
#4
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
toignitioncoil
.
Repair
Group
120
Code
1275
:
Ignitioncoil
#5
(DME
3
.3.1
only)
Test
ignition
coil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1276
:
Ignition
coil
#6
(DME
3
.3.1
only)
Test
ignitioncoil
and
wiring
loignitioncoil
.
Repair
Group
120
Code
1281
:
DME
control
module
memory
supply
(DME
3
.3
.1
only)
Check
voltage
supply
from
battery
lo
DME
control
module
.
Electri-
Code
1282
:
Fault
code
memory
(DME
3
.3.1
only)
Check
DME
control
module
inputs/outputs
.
Control
module
may
be
faulty
.
Repair
Group
130
Code
1283
:
Fuel
injector
output
stage
(DME
3
.3
.1
only)
Check
DME
control
module
inputs/outputs
.
Control
module
may
be
faulty
.
Repair
Group
130
DRIVEABILITY
TROUBLESHOOTING
cal
Wiring
Diagrams
al
Icld
Table
e
.
Engine
Driveability
Troubleshooting
c
l
1
I
f
I
I
Oxygen
sensor
faulty
Test
oxygen
sensor
.
ENGINE-GENERAL
100-
1
5
SYMPTOMS
a
.
Engine
fafs
tostart
b
.
Engine
startsbut
stops
immediately
c
.
Erratic
engine
idle
d
.
Poor
engine
responseon
acceleration
e
.
Erratic
engine
operation
in
al¡
speed
ranges
f
.
Excessive
fuel
consumption
g
.
Poor
enginepower,
fails
to
rev
up
h
.
CO
content
toolow
i.
CO
content
too
high
CAUSES
CORRECTIVE
ACTION
a
Fuel
pump
faulty
Test
fuel
pump
.
Repair
Group
160
a
e
Ignition
system
faulty
Test
ignition
system
.
Repair
Group
120
a
Main
relay
or
fuel
pump
relay
faulty
Test
main
relay
.
Repair
Group
130
a
Crankshaft/rpm
position
sensor
faulty
Test
crankshaft/rpm
sensor
.
120
b
c
h
i
ldle
speed
control
valve
faulty
Test
idle
speed
control
valve
.
c
d
e
Throttle
position
sensor
faulty
or
idle
signal
to
Test
throttle
position
sensor
.
DME
control
module
missing
.
c
d
h
i
Mass
air
flow
sensor
faulty
Test
mass
air
flow
sensor
Repair
Group
130
a
b
c
d
e
h
Large
air
intake
system
leak
Check
for
major
intake
air
leaks
downstream
of
mass
air
flow
sensor
.
a
c
d
e
g
h
Fuel
pressure
too
low
Test
fuel
pressure
.
Repair
Group
130
?
I
F
ue
l
pr
essu
r
e
t
oo
high
T
est
f
u
el
pressure
.
Repair
Group
130
d
e
g
h
Fuel
pump
delivery
volume
too
low
Test
fuel
pump
delivery
volume
.
Repair
Group
160
a
c
e
f
h
q
C
oo
l
a
nt
t
e
mp
e
r
a
t
u
r
e
se
n
so
r
f
au
lty
--]
T
est
coo
l
a
n
t
temp
erature
sensor
.
c
e
~
f
i
~
Fuel
injectors
leaking
Check
fuel
injectors
and
replace
leaking
injectors
.
~
Repair
Group
130
Throttle
plate
binding
or
incorrectly
adjusted
Check
throttle
plate
and
adjust
if
necessary
.
a
c
Electrical
connections
loose,
broken,
or
cor-
Visually
inspect
connectors
and
correct
any
roded
faults
.
Repair
Group
600
Ground
connections
loose,
broken,
or
corroded
Visually
inspect
ground
connections
and
correct
any
faults
.
Repair
Group
600
c
e
~
f
CO
content
too
high
Test
air
flowor
mass
air
flow
sensor
.
Repair
~
Group
130
a
b
c
d
e
CO
content
too
low
Test
mass
air
flow
sensor
.
gb
c
d
e
f
g
h
i
Inputsignals
to
ECM
missing,
ECM
in
limp
Make
electrical
tests
at
DMEECM
relay
.
Repair
home
mode
Group
130
a
~
b
~
c
~
d
e]
f
g
h
i
ECM
faulty
Test
DMEECM
inputs
.
If
all
inputs
are
correct,
replace
ECM
.
DRIVEABILITY
TROUBLESHOOTING
GENERAL
.
.
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.
.........
130-2
Intake
air
temperature
(IAT)
sensor,
Principles
of
Operatinn
.
.
.
.
.
.
.
.
.
.........
130-2
testing
and
replacing
...
.
...
.
.
.
.......
.
130-19
Basic
Engine
Settings
.
.
.
.
.
.
.
.
.
.
.
.
.
.
...
:
.
130-3
Throttle
position
sensor
(TPS),
DISA
(Dual
Resonance
Intake
System)
.
.
.
.
.
130-3
testing
and
replacing
...
.
...
.
.
.
.
.
...
.
.
.130-19
On-Board
Diagnostics
(OBD)
Idle
speed
control
valve,
testing
.
.
.
.
.
.
.
.
.
.
130-20
and
Fault
Diagnosis
.
.
....
.
......
.
.
.
...
130-4
Idle
speed
control
valve,
replacing
.
.
.
.
.
.
..
130-21
SecondaryAir
Injection
.
.
.....
.
.........
.
130-5
BOSCH
DME
M5
.2
COMPONENT
Warnings
and
Cautions
.
.
...
.
.
.
.........
.
130-6
REPLACEMENT
.....
.
......
.
....
.
.
.
..
130-21
ELECTRICAL
CHECKSAND
Mass
air
flow
sensor,
replacing
.
.
....
.
....
130-22
COMPONENT
TESTING
.
.
.
.
.
.
.
.
...
.
.
.
.
.
130-7
Engine
coolant
temperature
(ECT)
Main
sensor,
replacing
..
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
130-22
rela
y
testing
130
-7
,...
.
.
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.
Intake
air
temperature
(IAT)
sensor,
Fuel
pump
relay,
testing
.
.
.
.
.
.
.
...
.
.
.
.
.
.
.
130-7
rep
lacin
.
.
.
.
.
.
.
.
.
.
.g
.
.
.
.
.
.
.
...
.
.
.
..
.130-22
Oxygen
sensor,
testing
(Boschsystems
only)
130-8
Throttle
poson
sensor
(TPS)
replacing
13022
,
..
.-
FUEL
DELIVERY
TESTS
...
.
....
.
.
.
...
.
130-9
Idle
speed
control
valve,
replacing
...
.
....
.130-23
Operating
fuel
pump
for
tests
.
.
.......
.
...
130-9
SIEMENS
MS
41
.1
COMPONENT
Relieving
fuel
pressure
and
REPLACEMENT
.
...
.
.
.
.
.
.......
.
....
.130-23
connecting
fuel
pressure
gauge
......
.
..
130-10
Residual
fuel
pressure,
testing
.
.....
.
.
.
.
.
130-10
Mass
air
flow
sensor,
replacing
.
.......
.
.
.130-25
Fuel
pressure
regulator
response
Engine
coolant
temperature
(ECT)
to
engine
load,
testing
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
.
130-11
sensor,
replacing
.....
.
.
.
.
.
.........
.130-25
Fuel
rail
and
injectors,
checking
...
.
.
.
.
.
.
.
130-11
Intake
air
temperature
(IAT)
sensor,
replacing
.
.
.
.
.
.....
.
.
.
.
.
.
.
.......
.
.
.130-25
Fuel
rail
and
injectors,
replacing
..
.
.
.
.
.
.
.
130-12
Throttleposition
sensor
(TPS),
replacing
.
.
.
130-26
Fuel
PressureRegulator
.........
.
.
.
.
.
.
.
130-13
Idle
s
eed
control
valve,
re
lacin
130-26
Fuel
pressure
regulatorreplacing
p
p
g
.'''...
.
'
,
(fuel
rail
mount)
...
.
.
.
.
.
.............
130-13
ECM
PIN
ASSIGNMENTS
.............
.
.
130-26
Fuel
pressure
regulator,
replacing
Engine
control
module
(ECM),
accessing
...
130-26
(undercar
mount)
.
.
.
.
.
.
.
.
.........
.
.
130-14
BOSCH
DME
M1
.7
COMPONENT
TESTS
AND
REPAIRS
.
.
.
.
.
...
.
.
.
.
.
.
.
.
130-14
Air
flow
sensor,
testing
and
replacing
.
.
.
.
.
.
130-14
Engine
coolant
temperature
(ECT)
sensor,
testing
and
replacing
...
.
.
.
.
.
.
.
.
130-15
Throttle
position
sensor
(TPS),
testing
and
replacing
.
..........
.
.....
130-16
Idle
speed
control
valve,
testing
and
replacing
.
.
.
.
.
............
130-16
BOSCH
DME
M3
.1
AND
M33
.1
COMPONENT
TESTS
AND
REPAIRS
.
.
.
130-17
Mass
Air
Flow
Sensor
.
.
.
.
.
.
.
.
.....
.
.
.
.
.130-17
Mass
air
flow
sensor
(hotwire),testing
and
replacing
.
.
.
.
.
.....
.
.
.
.
.
.
.
130-17
Mass
air
flow
sensor
(hot
film),
testíng
and
replacing
.
.
.
.....
.
.
.
.
.
.
.
.
.
130-18
Engine
coolant
temperature
(ECT)
sensor,
testing
and
replacing
..
.
.
.
.
.
...
.
130-18
130
Fuel
i
n
jection
FUEL
INJECTION
130-1
TABLES
a
.
Engine
Management
System
Variants
.........
.130-2
b
.
Mass
Air
Flow
Sensor
Variants
..
.
..
..........
.130-2
c
.
Fuel
Pressure
Specifications
..
.
.
...
..........
130-11
d
.
Engine
Coolant
Temperature
Sensor
or
Intake
Air
Temperature
Sensor
Test
Values
(DME
1
.7)
...
.
130-15
e
.
ThrottlePosition
Sensor
Tests
(DME
1
.7)
......
.130-16
f
.
Engine
Coolant
Temperature
Sensor
or
Intake
Air
Temperature
Sensor
Test
Values
(DME
3
.1/3
.3
.1)130-19
g
.
Throttle
Position
Sensor
Tests
(DME
3
.1/3.3
.1)
.
.130-20
h
.
ECM
Pin
Assignment-Bosch
DME
M1
.7
....
.
..
.130-28
i.
ECM
Pin
Assignment-Bosch
DME
M3
.1
.......
.130-30
j
.
ECM
Pin
Assignment-Bosch
DME
M3
.3
.1
.....
.130-32
k
.
ECM
Pin
Assignment-Bosch
DME
M5
.2
.......
.
130-34
I.
ECM
Pin
Assignment-Siemens
DME
MS
41
.1
..
.
130-36
ELECTRICAL
CHECKS
AND
COMPONENT
TESTING
Main
relay,
testing
The
main
relay
is
energized
via
the
engine
control
module
and
supplies
plus
(+)
power
to
the
many
of
the
engine
man-
agement
components
and
subsystems,
including
the
fuel
pump
relay
.
If
this
relay
is
faulty,
the
engine
will
not
start
.
1
.
With
ignition
off,
remove
main
relay
.
See
Fig
.
6
.
.
iommooommmoi
~
"""
Fuel
DME
sensor
CA
UTION-
Relay
positions
can
vary
.
Be
sure
to
confirm
relay
position
by
identífyíng
the
wiring
in
the
socket
us-
ingthe
wiring
diagramsfound
at
the
rearof
this
manual
.
0013034)
Fuel
pump
relay,
testing
FUEL
INJECTION
130-
7
87
851186
30
~j
1
.
Remove
fuel
pump
relay
from
its
socket
.
87661
Fig
.
7
.
Check
for
battery
voltage
at
main
relay
terminals
30
and
86
.
Voltage
should
be
present
at
all
times
.
4
.
With
ignition
on
and
relay
installed,
check
for
battery
voltage
at
terminals
87
.
"
If
battery
voltage
is
present,relay
has
energized
and
is
functioningcorrectly
.
"
lf
battery
voltage
is
not
present
and
al¡
earlier
tests
are
OK,
relay
is
faulty
and
should
be
replaced
.
Fig
.
6
.
Engine
management
relays
in
the
power
distribution
box,
left
rear
of
engine
compartment
.
The
fuel
pump
relay
is
located
in
the
power
distribution
box
.
Refer
to
Fig
.
6
.
The
ECM
supplies
power
to
the
coil
side
of
the
fuel
pump
re-
lay
.
During
starting,
the
fuel
pump
runs
as
long
as
the
ignition
switch
isin
the
start
position
and
continues
to
run
once
theen-
gine
starts
.
If
the
relay
ís
faulty
the
fuel
pump
will
notrun
.
2
.
Check
for
voltage
at
terminal
30
and
terminal
86
of
re-
¡ay
socket
.
See
Fig
.
7
.
2
.
With
key
off,
check
for
batteryvoltage
at
socket
terminal
"
If
battery
voltage
is
present
continue
testing
30
.
See
Fig
.
8
.
"
lf
battery
voltage
is
not
present
at
either
point,
check
large
red
wire
in
relay
socket
.
See
Electrical
Wiring
3
.
With
ignition
key
in
start
position
check
for
battery
volt-
Diagrams
.
age
at
terminal
86
.
NOTE-
4
.
With
ignition
key,
use
digital
multimeter
to
check
for
The
wiring
to
terminals
85
and
86
in
the
main
relay
may
ground
at
terminal
85
.
be
reversed
.
Electrically,
the
relay
functions
either
way
.
lf
voltage
ís
not
present
at
terminal
86,
check
for
volt-
NOTE-
age
at
terminal
85
.
The
ground
atterminal
85
is
switched
by
the
ECM
.
The
ECM
hamess
must
be
connected
to
check
the
3
.
Reinstall
relay
and
turn
ignition
on
.
Gainaccess
to
un-
switched
ground
connection
.
derside
of
relay
socket
and
check
for
ground
at
terminal
85
(brown
wire)
.
5
.
If
no
faults
are
found
up
tothis
point,
testfuel
pump
op-
"
lf
ground
is
present
continue
testing
.
eration
as
described
in
160
Fuel
Tank
and
Fuel
Pump
.
"
If
ground
is
not
present,
signal
from
ECM
is
missing
.
Check
wire
between
ECM
and
relay
.
If
no
faults
can
be
found,
ECM
may
be
faulty
.
ELECTRICAL
CHECKS
AND
COMPONENT
TESTING
130-
8
FUEL
INJECTION
Fig
.
8
.
Fuel
pump
relayterminal
identification
.
1.
Peel
back
rubber
boot
on
oxygen
sensor
electrical
har-
ness
connector
(car
wiring
side)
.
With
connector
at-
Oxygen
sensor,
testing
tached
to
sensor,
connect
digital
voltmeter
to
pins
1
(BOSch
systems
only)
and
2
in
rear
of
connector
.
See
Fig
.
10
.
CAUTION-
"
The
information
inthis
sectionapplies
to
Bosch
engine
management
systems
only
.
"
The
Siemens
MS
41
.1
system
uses
resistive-type
oxygen
sensors
.
This
sensor
uses
a
5-volt
refer-
ence
signal
input
and
the
output
to
the
ECM
var-
ees
from
1-5
volts,
in
stepped
increments
based
on
oxygen
content
in
the
exhaust
.
NOTE-
"
On
pre-08D
11(1992-1995)
cars,
there
is
one
oxygen
sensor
mounted
upstream
of
the
catalytic
convert-
er(s)
in
the
exhaust
pipe
.
See
Fig
.
9
.
"
On
OBD
11
cars
(1996-1998)
cars,
there
is
one
oxygen
sensor
before
andone
after
each
catalytic
converter
.
"
OnM52
and
S52US
engines,
the
front
pairof
oxygen
sensors
are
installed
in
the
exhaust
manifolds
.
The
oxygen
sensor
providesan
input
voltage
signal
(0-1
VDC)
to
the
ECM
based
on
the
oxygen
content
in
the
exhaust
gas
.
TO
generate
voltage,
the
sensor
temperature
must
exceed
575°F
(300°C)
.
Therefore
it
ís
electrically
heated
.
NOTE-
"
The
test
given
below
is
not
a
conclusive
test
of
oxygen
sensor
efficiency
and
does
not
test
how
quickly
the
oxygensensor
can
react
to
changing
conditions
.
"
Pin
numbers
and
wirecolors
can
vary
.
Always
check
the
wiring
diagrams
to
conflrm
wire
color
and
pinas-
signment
.
ELECTRICAL
CHECKS
AND
COMPONENT
TESTING
0013135
Fig
.
9
.
Oxygen
sensor
location
(arrow)
ahead
of
catalytic
converter
.
3181
model
with
M42
engine
shown
.
1
.
Black
(ground)
2
.
Grey
(signal)
4
.
White
(heater
circuit)
3
.
White
(heater
circuit)
0013189
Fig
.
10
.
Oxygen
sensor
connector
terminal
identification
(sensor
sede)
.
Terminals
numbers
are
molded
into
connector
.
2
.
Start
engine
.
Oxygen
sensorshould
start
to
output
a
fluctuating
voltage
within
a
short
period
.
If
voltage
is
in-
correct,
turn
engine
off
and
check
preheater
circuit
as
described
below
.
WARNING
-
Exhaust
manifolds
and
pipes
can
be
hot
enough
to
cause
serious
burns
.
Wear
suitable
heavy
gloves
and
other
appropriate
protection
.
Oxygen
Sensor
FUEL
DELIVERY
TESTS
FUEL
INJECTION
130-
9
"
Voltage
at
¡dle
..
.
..
..
....
0
.2
to
0
.8
VDC,
fluctuating
Checking
fuel
delivery
is
afundamental
part
of
trouble-
shooting
and
diagnosing
the
engine
management
system
.
Fuel
pressure
directly
influences
fuel
delivery
.
An
accurate
NOTE-
fuel
pressure
gauge
will
be
needed
to
make
the
tests
.
To
check
sensorresponse
to
lean
and
rich
mixtures,
createenairleak,
orpull
vacuumhoseofffue¡
pressure
There
are
three
significant
fuel
delivery
values
to
be
mea-
regulator
to
increase
fuel
pressure
.
sured
:
3
.
Separate
sensorharness
connector
from
sensor
.
Check
for
battery
voltage
between
terminals
3
and
4
(green
wire
and
brown
wire)
in
main
wiring
harness
side
of
con-
nector
with
engine
running
.
If
voltage
is
not
present,
check
oxygen
sensor
heater
relay
.
See610
Electrical
Component
Locations
.
4
.
Check
heater
element
resistance
between
terminals
3
and
4
in
sensor
side
of
connector
.
If
element
is
electri-
cally
open
(no
continuity),
replace
sensor
.
NOTE-
The
oxygen
sensor
heater
relay
is
mounted
in
the
main
power
distributfon
box
in
the
left
rear
of
the
engine
com-
partment
.
Refer
to
Fig
.
6
.
The
heater
relay
is
energized
wíth
positive
(+)
battery
voltage
from
the
main
relayanda
switched
ground
from
the
ECM
.
See
Electrical
Wir-
ing
Diagrams
.
"
Oxygen
sensor
to
exhaust
pipe
...
..
55
Nm
(41
ft-Ib)
"
System
pressure-created
by
the
fuel
pump
and
main-
tained
by
the
pressure
regulator
.
"
Fuel
delivery
volume-created
by
the
fuel
pump
and
af-
fected
by
restrictions,
suchasclogged
fuel
filter
.
"
Residual
pressure-the
pressure
maintained
in
the
closed
system
after
the
engine
and
fuel
pump
are
shut
off
.
Procedures
for
measuring
the
first
two
quantities
arede-
scribed
in
160
Fuel
Tank
and
Fuel
Pump
.
Residual
fuel
pres-
sure
is
checked
using
the
procedure
detailed
later
in
this
group
.
Operating
fuel
pump
fortests
To
operate
the
fuel
pump
for
testing
purposes
without
hav-
íng
to
runthe
engine,
the
fuel
pump
relay
can
be
bypassed
to
power
the
pump
directly
.
Fuel
pump
relay
location
is
shown
in
Fig
.
6
.
5
.
¡f
oxygen
sensor
doesn't
produce
a
fluctuating
voltage
To
runthe
fuel
pump,
remove
the
fuel
pump
relay
and
con-
and
preheater
circuit
is
OK,
replace
sensor
.
nect
the
socket
for
relayterminal
30
to
the
socket
for
relay
ter-
mina¡
87
with
a
fused
jumper
wire
.
After
completing
the
tests,
NOTE-
remove
the
jumper
wire
.
If
not
already
applied,
coat
the
oxygen
sensor
threads
with
an
anti-seize
compound
before
installation
.
Do
not
CAUTION-
getthe
compound
on
the
sensor
tip
.
"
Relay
locations
may
vary
.
Use
care
when
identi-
fying
relays
and
making
electrical
checks
at
the
fuselrelay
panel
.
See
610
Electrical
Compo
Tightening
Torque
nent
Locations
for
additional
relay
information
.
"
The
fuel
pump
relay
has
a
1
.5
mm2
red
wire
at
ter-
minal
30
in
the
relay
socket
.
Terminal
87
has
a
1
.5
mm
2
greenlviolet
wire
.
See
Electrical
Wiring
Di-
agrams
for
additional
wiring
information
.
NOTE-
Thejumper
wire
should
be
1.5
mm2
(14
ga
.)
and
in-
clude
an
in-line
tuse
holder
with
a15
amp
tuse
.
To
avoid
fuselrelay
panel
damage
from
repeated
connect-
ing
and
disconnecting,
also
include
a
toggle
switch
.
A
heavy-duty
jumper,
BMW
tool
no
.
61
3
050,
is
also
available
from
an
authorized
BMW
dealer
.
FUEL
DELIVERYTESTS