check engine light BMW 525i 2001 E39 Workshop Manual

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I General Warnings and Cautions
WARNINGS (continued)
. The air conditioning system is filled with chemical refrigerant,
which is hazardous. The AIC system should be serviced only by
trained technicians using approved refrigerant recoverylrecycling
equipment, trained in related safety precautions, and familiar with
regulations governing the discharging and disposal of automotive
chemical refrigerants.
. Do not expose any part of the AIC system to high temperatures
such as open flame. Excessive heat will increase system pres-
sure and may cause the system to burst.
Some aerosol tire inflators are highly flammable. Be extremely
cautious when repairing a tire that may have been inflated using
an aerosol tire inflator. Keep sparks, open flame or other sources
of ignition away
from the tire repair area. Inflate and deflate the
tire at least four
times before breaking the bead from the rim.
Completely remove the tire from the rim before attempting any re-
pair.
Cars covered by this manual are equipped with a supplemental
restraint system (SRS), that automatically deploys
airbags and
pyrotechnic seat belt tensioners
In the event oi a frontal or side
impact. These are explosive devices. Handled improperly or with-
out adequate safeguards, they can be accidently activated and
cause serious injury.
- The ignition system produces high voltages that can be fatal.
Avoid contact with exposed terminals and use extreme care when
working on a car with the engine running or the ignition switched
on.
. Place jack stands only at locations specified by the manufacturer.
The vehicle
illtino iack su~olied with the vehicle is intended fortire -. , . changes only. A heavy duty floor jack should be used lo lift vehicle
before installing
jacl( stands. See 010 General.
- Battery acid (electrolyte) can cause severe burns. Flush contact
area
with water, seek medical attention.
Aerosol cleaners and solvents may contain hazardous or deadly
vapors and are highly flammable. Use only in a well ventilated ar-
ea. Do not use on hot surfaces (engines, brakes, etc.).
Do not remove
coolant reservoir or radiator cap with the engine
hot. Danger of burns and engine damage.
CAUTIONS-
See also WARNINGS
- if you lack the slqills, tools and equipment, or a suitable worl(shop
for any procedure described in this manual, leave such repairs to
an authorized BMW dealer or other qualified shop.
BMW is constantly improving its cars and sometimes these
changes, both in parts and specifications, are made applicable to
earlier models. Therefore, part numbers listed in this manual are
for reference only. Always check with your authorized BMW deal-
er parts department for the latest information.
Before starting a job, make certain that you have all the neces-
sary tools and parts on hand. Read ail the instructions thorough-
ly, and do not attempt shortcuts. Use tools appropriate to the
work and use only replacement parts meeting BMW specifica-
tions.
Use pneumatic and electric tools only to loosen threaded parts
and fasteners. Never use these tools to tighten fasteners, espe-
cially on light alloy parts. Always use a torque wrench to tighten
fasteners to the tightening torque specification listed.
Be mindful of the environment and ecology. Before you drain the
crankcase, find out the proper way to dispose of the
oil. Do not
pour
oil onto the ground, down a drain, or into a stream, pond or
lake. Dispose of waste in accordance with Federal, State and
Local laws.
The control module for the anti-lock brake system
(ABS) cannot
withstand temperatures from a paint-drying booth or a heat
lamp
in excess of 203" F (95°C) and should not be subjected to tem-
peratures in excess of 185°F
(8S°C) for more than two hours.
- Before doing any electrical welding on cars equipped with ABS,
disconnect the battery negative
(-) terminal (ground strap) and
the ABS control module connector.
- Always make sure ignition is off before disconnecting battery.
Label battery cables before disconnecting. On some models, bat-
tery cables are not color coded.
Disconnecting the battery may erase fault code@) stored in control
module memory. Using special BMW diagnoslic equipment, check
lor
iauit codes prior to disconnecting the battery cables. If the mal-
I.mct on ndicator Ignt (MIL) s I. ..minaled. see OBD On-Board
Diaanostics
Tl11s iant is iuenlfted as lne Check Ena~ne oht
(1997-2000 models jor~ervlce Engine Soon light (2061 andlater
models). If any other system iaults have been detected (indicated
by an illuminated warning light), see an authorized BMW dealer.
If a normal
or rapid charger is used to charge battery, the battery
must be disconnected and removed from the vehicle in order to
avoid damaging the vehicle.
- Do not quick-charge the battery (for boost starting) for longer
than one minute. Wait at least one minute before boosting the
battery a second time.
* Connect and disconnect a battery charger only with the battery
charger switched off.
- Sealed or "maintenance free" batteries should be slow-charged
only, at an amperage rate that is approximately 10% of the bat-
tery's ampere-hour (Ah)
rating.
. Do not allow battery charging voltage to exceed 16.5 volts. If the
battery begins producing gas or boiling violently, reduce the
charging rate.
Boosting a sulfated battery at a high charging rate
can cause an explosion.

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General
Cars with discharged or dead batteries can be jump-started
using the good battery from another car. See owner's manual
for proper instruction on jump starting. When jump-starling
the engine, always note the following warnings.
4 Lower car. With all wheels on ground, fully tighten nuts in a
WARNING-
* Battery acid (electrolyte) can cause severe burns, and will
damage the
cal; clothing, and you. If electrolyte is spilled,
wash the surface with large quantities of water.
M itgets into
eyes, flush them with water for several minutes and call a
doctor.
B4
5
43
2 BOOIFNG.
Batteries produce explosive and noxious gasses.
Keeps sparks and flames away. Do not smoke near
batteries.
Do notjump-start the engine
ifyou suspect that the bat-
tery is frozen. Trappedgas may explode. Allow the bat-
tery to thaw first.
Do not quick-charge the battery (for boost starting) for
longer than one minute, and do not exceed
16.5 volts
at the battery with the boosting cables attached. Wait at
least one minute before boosting the battery a second
time.
crisscross pattern.
Torque wheel nuts when installing wheel.
Check inflation pressure of spare tire.
Tightening torque
Wheel to wheel hub 120 Nm (89 ft-ib)
Jump starting
Indicator and warning lights
Many vehicle systems are self-monitored for faults while driv-
ing. Generally,
a red warning lamp that comes on during driv-
ing should be considered serious. If you cannot immediately
determine the seriousness of the warning light, stop the vehi-
cle in a safe place and turn the engine off as soon as possible.
Consult the owner's manual for additional information on the
warning lamp and the recommended action.
If the Malfunction Indicator Lamp (MIL)
(Check Engine or Ser-
vice Engine Soon warning light) comes on orflashes, it indi-
cates that an emissions-related fault has occurred. Faults
such as a bad oxygen sensor or a dead fuel injector can
cause the exhaust or evaporative emissions to exceed a
specified limit. When these limits are exceeded, the MIL will
be turned on. The engine can be safety driven with the light
on, although the emission systems should be
checked as
soon as possible. See OBD On-Board Diagnostics for

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01 0-20
General
more information on the Check Engine Light and the on-
board diagnostic system.
Towing
The cars covered by this manual should be towed with a tow
truck using wheel lift or flat bed equipment. Do not tow the car
on all four wheels except
forvery short distances to move it to
a safe place.
CA U JION-
Do not tow with sling-type equipment The front spoilers and
b~m~er covers may sustain damage.
4 To access threaded towing eye socltet, pry open trim on front
or rear bumper.
NOJE-
A towing eye is provided in the luggage compartment tool lcit.
The towing eye can be screwed into the front or rear bumper.
4 Install towing eye into threaded hole.
- Standard transmission: Do not tow with rear wheels on
ground unless absolutely necessary.
- Automatic transmission: Have rear wheels placed on dollies,
or use flat bed truck. Use towing eye for winching vehicle on
flat bed.
CAUTION-
Automatic transmission fluid (ATF) does not circulate when
I the car is towed. Severe transmission damage may result.
NOTE-
Be sure transrnission fluid has been topped off before
starting tow.
Always tow car with transrnission lever in
N (neutral).
. ATF draining and filling is covered in 240 Automatic
Transmission.
Be sure to read the filling and draining pro.
cedure, as special service equipment is required to
checlc
the fluid level.

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--- -
Maintenance
Table b. Inspection I Service (continued)
I I I I
Warm engine Dealer service
required recommended
Check windshield
washer fluid level and
antifreeze protection.
Add washer fluid as necessary.
Replace ventilation
microfilter. (Note:
reduce replacement intervals in dusty
operation conditions)
Reset Service interval Indicator
(Sil).
Additional
repair
information
Tools Required
*
eck aim of washer jets and adjust if
necessary.
covers, obvious damage or attachment o
s or accessories.
Road test
Check braking performance, steering,
heating and air conditioner operation.
Check manual transmission and clutch
operation or automatic transmission
operation. New
parts
required
*
Bodylelectrical
121
630
630
Checic battery state of charge
Check operation of:
headlights,
parking iights, back-up lights.
license plate lights, interior lights,
glove box
illumination, engine compartment light,
trunk light, turn signals, emergency
flashers, stop iights.
Check operation of horn and headlight
dimmer switch
:i:

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020-1 4
Maintenance
- When oil flow has diminished to an occasional drip, reinstall
drain plug with a new metal sealing washer and torque plug.
Tightening torque Engine oil drain plug to oil pan
25 Nrn (1.8 ft-lb)
6-cylinder oil filter assembly
r------ 1
< Working at oil filter housing (1):
Lubricate and install new oil filter O-rings (3, 4).
Install a new filter cartridge (5).
lnstall and tighten housing cover (2).
6-cylinder oil filter assembly shown, V-8 is similar.
Tightening torque Cover to oil filter housing
25 Nm (1.8 it-lb)
- Refill crankcase with oil. Approximate oil capacity is listed in
Tabled. Engine oil with filter change. Use dipstick to
check correct oil level.
- Start engine and check that oil pressure warning light
immediately goes out.
- Allow engine to run fora few minutes to circulate new oil, then
check for leaks at drain plug and oil filter. Stop engine and re-
check oil level
The section describes other routine maintenance done in the
engine compartment. Information on engine oil service is
giv-
enkar~ier inthis group.
For these procedures, it is not necessary for the car to be
raised and supported off the ground.
Accelerator and linkage
The accelerator and linkage at the throttle housing should be
lubricated periodically. Use ageneral purposeoil on the joints
and bearings of the linkage. Use a multipurpose grease on
the bearing points of the throttle plate.
Air filter, replacing
The specified replacement intervals forthe air filter are based
on normal use. If the car is operated primarily in dusty
conditions, the air filter should be serviced more frequently.

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020-22 Maintenance
1
- Installation is reverse of removal, bearing in mind the
following:
Lightly lubricate new
spark plug threads with
copper-based anti-seize compound.
Thread plugs into cylinder head by hand to prevent
cross-threading.
. Be sure to reinstall and tighten coil grounds.
Tightening torque Spark plug
to cylinder head 25 Nm (18 It-lb)
Interior ventilation microfilter, replacing
Two interior ventilation microfilters are used, one on each
side of the engine compartment at the fire wall.
< To replace the microfilter, unclip the wire fastener and
remove the cover.
Lift out the filter, and replace. Left side shown; right is
similar.
Replace cover and clip wire fastener to retain cover.
Battery, checking, cleaning, and replacing
The battery Is located in the right side of the luggage compart-
ment. Simple maintenance of the battery and its terminal
connections will ensure maximum starting periormance,
especially in winter when colder temperatures reduce battery
power.
Battery cables should be tight. The terminals, cable clamps
and battery case should be free of the white deposits that
indicate corrosion and acid salts. Even a thin layer of dust
containing conductive acid salts can cause battery discharge.

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Two common causes of driveability problems are incorrect
system voltage and bad grounds.
System voltage
Digital motor electronics (DME) requires that the system (bat-
tery) voltage be maintained within a narrow range of DC volt-
age.
DC voltage levels beyond or below the operating range,
or any
AIC voltage in the electrical system can cause havoc.
When troubleshooting an illuminated MIL, make sure the bat-
tery is fully charged and capable of delivering all its power to
the electrical system. An undercharged battery can amplify
AIC alternator output ripple.
To
make a quick check of the battery charge, measure the
voltage across the battery terminals with all cables attached
and the ignition off.
Afully charged battery will measure 12.6
volts or slightly more, compared to 12.1 5 volts for a battery
with a 25% charge.
The DME system operates at low voltage and current levels,
making it sensitive to small increases in resistance. The elec-
trical system is routinely subjected to corrosion, vibration and
wear, so faults or corrosion in the wiring harness and connec-
tors are not uncommon. Check the battery terminals
forcorro-
sion or loose cable connections. See 121 Battery, Starter,
Alternator for additional information.
If a battery cable connection has no
v~sible faults but is still
suspect, measure the voltage drop across the connection. A
large drop indicates excessive resistance, meaning that the
connection is corroded, dirty, or damaged. Clean or repairthe
connection and retest.
NOTE-
For instructions on conducting a voltage drop test and other
general electrical troubleshooting information, see
600 Elec-
trical System-General.
Visually inspect all wiring, connectors, switches and fuses in
the system. Loose or damaged connectors can cause inter-
mittent problems, especially the small terminals in the ECM
connectors. Disconnect the wiring harness connectors to
check for corrosion, and use electrical cleaning spray to re-
move contaminants.
Main grounds
Good grounds are critical to proper DME operation. If a
ground connection has no visible faults but is still suspect.
measure the voltage drop across the connection. A large volt-
age drop means high resistance. Clean or repair the connec-
tion and retest.
LBuntr.yP~sbhnllcn.can#-AII A,~iltl Rcsrwsd

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110-3
Engine Removal and lnstallationl
Q Fuel line plugs
(Tool No.
BMW 13 5 281 / 13 5 282)
4 Fuel line removal tool
(Tool No.
BMW 16 1 050)
CAUTION-
Disconnecting the battery may erase fault code@) storedin
memoiy Check for fault codes prior to disconnecting the
battery cables.
If the MIL (Malfunction Indicator Light, also may be
called "Check Engine" or "Service Engine Soon" light)
is illuminated, see
OBD On-Board Diagnostics for
DME fault code information.
It orhersysrem faults have been detected, as indicated I
by an ~llum~nated ABS, SRS orASC/DSC ~arning light,
see the appropriate repair group in this manual or an
authorized BMW dealer for more information on fault
codes.
NOTE- Engine removal procedures are similar for all 6-cylinder
models. When differences
exist, they are noted at the be-
ginning of each step. Engine are referred to by engine
code. See
100 Engine-General for engine code and appli-
cation information.
@ Be sure to cover all painted surfaces before beginning the
removal procedure. As an aid to installation, label all com-
ponents, wires and hoses before removing them. Do not
reuse
gaskets, O-rings or seals during reassembly.
The
intake manifold must be removed on &cylinder mod-
els before the engine can be removed.
WARNING-
Due to risk of personal injury, be sure the engine is cold be-
fore beginning the removal procedure.

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113-5
Cylinder Head Removal and Installation I
< Fuel line plugs
(Tool No.
BMW 13 5 281113 5 282)
4 Fuel line removal tool for quick-disconnect fittings
(Tool No.
BMW 16 1 050)
< Tensioning bracket (V-8)
(Tool No. BMW 11 7 380)
Compressed air fitting for testing VANOS operation
((Tool No.
BMW 11 3 450)
< Upper timing cover installation tool set, V-8
(Tool No. BMW 11 1 41 0)
Cylinder compression, checking
A compression gauge is needed to make a compression test.
For accurate test, the battery and starter must be capable of
cranking the engine at least
300 rpm, and the engine should
be at normal operating temperature.
NOTE-
Performing a compression test may cause a fault to set in the
ECM and may illuminate the Malfunction
Indicator Light
(MIL). The light can only be turned out using either
BMW
special service scan tools or an equivalent aftermarket scan
tool. Disconnecting the battery will not erase the fault memo-
ry or turn out the light. See OBD On-Board Diagnostics.

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I Cylinder Head Removal and Installation
4 Check that two locating dowels are correctly positioned in
block and are not damaged.
- Apply permanently elastic sealing compound Three Bond
1209 8 to joints where cylinder block joins timing case cover.
- Place new cylinder head gasket on cylinder block.
NOTE-
The word "OBEN" or 'TOP': printed on the gasket, should
face up. The cylinder head
gasket will fit correctly in only one
orientation.
- With camshafts locked in TDC oosition with BMW soecial
tools as described during cylinder head removal,
seicylinder
head in position, guiding primary chain through cylinder head
opening.
NOTE-
* The camshafts must be locl(ed in the TDC position at the
rear of the cylinder head with
BMW special tool I1 3 240
before installing the cylinder head.
Make sure the
cranksha% which had been rotated approx-
imately
30" opposite the direction of engine rotation, is still
in that position before lowering the cylinder head into posi-
tion.
- Lightly lubricate new cylinder head bolts. Loosely install bolts
and their washers, then thread them in until they are finger
tight.
NOTE-
. Torx-type cylinder head bolts should not be reused. They
are stretch-type bolts and must always be replaced when-
ever loosened.
Check that all washers for the cylinder head bolts are in
place before installing the bolts. Some of the washers may
be
stalced to the cylinder head.
CAUTIOI\C
Cylinder head bolts for a cast iron engine block are different
length and require different tightening torque than bolts for an
aluminum cylinder bloclc engines
(95 rnm versus 110 rnm
bolts).
- Install cylinder head-to-lower timing chain cover bolts finger
tight.
< Tighten cylinder head bolts in correct sequence to initial
torque value.