2001 BMW 525i manifold

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Exhaust systeml
M54 engine
(5301 2001-2003)
Clamping sleeve
Front muffler Rear muffler
Hanger
Vibration dampener
Clamping sleeve
Center muffler
Hanger
Gasket (front pipe to manifold)
10. Exhaust
manifold/catalytic
converter assemblies
11. Oxygen sensors, post-catalytic converter
12. Oxygen sensors, pre-catalytic converter

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I Exhaust System
M62 engine
(540i 1997-1 998)
1. Right side catalytic converters
2. Support bracket
3. Support bracket
4. Center muffler
5. Hanger
6. Rear muffler
7. Clamping sleeve
8. Oxygen sensors, post-catalytic
converter
9. Oxygen sensors, pre-catalytic
converter
10. Left side catalytic converter
11. Sealing rings
12. Left front exhaust manifold
13. Left rear exhaust manifold
14. Gasket
15. Exhaust manifold, right front
16. Exhaust manifold, right rear

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Exhaust systeml
M62 TU engine
(540i 1999-2003)
1. Oxygen sensors, pre-catalytic
converter
(2)
2.
Oxygen sensors, post-catalytic
converter
(2)
3.
Hanger
4. Rear muffler
5. Clamping sleeve
6. Hanger
7. Center muffler
8. Clamping sleeve
9. Catalytic converter, left side
10. Catalytic converter, right side
11. Exhaust manifoldlcatalytic
converter,
left side
12. Gasket (2)
13.
Gasket (2)
14.
Exhaust manifoldlcatalytic
converter, right side

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Brakes
The brake booster is mounted to the bulkhead on driver's side
of the engine compartment, directly behind the brake master
cylinder. Intake manifold vacuum acts on a large diaphragm
in the brake booster to reduce brake pedal effort.
Brake booster check valve
The checlc valve in the bralte booster vacuum line prevents
contamination from engine backfires and other sources from
entering the bralte booster.
Location of
check valve varies, depending on year and mod-
el.
4 6-cylinder models (528i):
1. Intake manifold
2 Hose clamp
3. Vacuum line
4. Upper hose bracket
5. Grommet 6. From 911998: Check valve in grommet in booster.
Remove left ventilation filter housing for access.
7. To 911 998: Check valve in vacuum hose. Remove left
ventilation filter housing, peel back trim rubber below
housing and
unclip upper hose brackets to access hose
clamps and valve.
8. Lower hose
bracket
9. Brake master cylinder
10. Brake booster
< 6-cylinder models (525i, 530i): Remove left ventilation filter
housing to access
checlc valve.
1. Vacuum hose
2. Hose clamp
3. Hose bracket
4. Check valve in grommet in booster
5.
Braite master cylinder
6. Grommet
7. Brake booster
4 V-8 models (540i) to 911998: Check valve (arrow) in vacuum
line behind left cylinder head.
- V-8 models (540i) from 911998: Checkvalve in brake booster.
Remove left ventilation filter housing to access valve.

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Brakes
- Pump brake pedal a few times to reduce vacuum in brake
booster. This makes removal of
check valve easier.
- Remove or loosen hose clamp(s) at check valve.
- Disconnect hoses. Remove valve to test or replace.
NOTE-
If valve is pressed into grommet in vacuum booster, pry it out
carefully.
- Reinstall valve using new hose clamps
NOTE-
Install the valve so that the molded arrow is pointing toward
the intake manifold.
Brake booster, removing and installing
CAUTIO&
All E39 vehicles sold in the USA are equipped with Antiloclc
Braking System (ABS) and either Automatic Stability Control
(ASC) or Dynamic Stability Control (DSC). In order for the
bralchg and stability controls to work properk if brake fluid
lines are disconnected and reconnected,
male sure that the
brake system is bled by an authorized BMW dealer or other
qualified repair facility using the BMW Service Tester: See
Brake Bleeding earlier in this group.
- Disconnect negative (-) cable from battery.
I CAUTION- I
Prior to disconnecting the battery read the battery discon-
nection cautions given in
001 General Cautions and
I Warnings. I
- Remove bralte master cylinder as described earlier.
- Disconnect engine vacuum hose from bralte booster.

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1 Brakes
Pull down panel
If applicable, disconnect electrical harness
rows) from 16-pin OBD-ll plug.
Remove panel from interior. connectors
(ar-
Working
above and in front of pedals, remove locking clip (A)
and slide brake booster pushrod off bralte pedal pin. Remove
brake booster mounting nuts
(6).
Working in engine compartment, carefully separate bralte
booster from engine compartment bulkhead.
CAUTION-
Do not use force on booster when separating from bulkhead.
This can damage booster and pushrod.
Remove booster by tilting out in direction of engine. Lift
booster up and out of engine compartment.
- Installation is reverse of removal, noting the following:
Make sure all nuts, fluid couplings, thread bores and mat-
ing surfaces are clean.
Replace bralte booster self-locking mounting nuts.
Replace sealing O-ring between master cylinder and bralte
booster.
Bleed bralte system as described earlier.
CAUTION--
Do not over-torque tlie master cylinder mounting bolts.
This could damage the
bralce booster and prevent proper
vacuum build-up.
After
30 minutes of use recheclc the torque on bralce
booster mounting nuts.
Tightening torques
Brake master cylinder to brake booster
26 Nm (19 it-lb)
Brake booster to bulkhead 22 Nm (16 it-lb)
(Recheck torque after
30 minutes of use.)
Brake fluid line to master cylinder 18 Nm (13 it-lb)
NOTE-
When replacing the brake booster check valve or vacuum
hose, install the valve so that the molded arrow is pointing to-
ward the
fntalce manifold. Use new hose clamps

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On-Board Diagnostics
Catalyst monitoring. Thisstrategy monitors the outputofthe
precatalyst and post-catalyst oxygen sensors, comparing the
oxygen content going into the catalytic converter to the
oxygen leaving the converter.
The diagnostic executive
lknows that most of the oxygen
should be used up during the oxidation phase. If it detects
higherthan programmed values, afault is set and the MIL
illuminates.
Misfire detection. This strategy monitors crankshaft speed
fluctuations and determines if an enoine misfire occurs bv
monitoring variations in speed between each crankshaft
sensortrigger point. This strategy is so finely tuned that it can
determine the severity of the misfire.
The system determines
if a misfire is occurring, as well as
other pertinent misfire
information such as:
Specific
cylinder(s)
Severity of the misfire event
Emissions relevant or catalyst damaging
Misfire detection is an on-going monitoring process that is
only disabled under certain limited conditions.
Secondary air injection monitoring. Secondary air
injection is used to reduce HC and CO emissions during
engine warm up. Immediately following a cold engine start
(-1 0" to 40°C), fresh air (and therefore oxygen) is pumped
directly into the exhaust
manifold. By injecting additional
oxygen into the exhaust manifold, catalyst warm-up time is
reduced.
Secondary air system components are:
Electric air injection pump
* Electric pump relay
* Non-return valve
Vacuum
I vent valve
- Stainless steel air injection pipes
Vacuum reservoir
The secondary air system is monitored via the use
of the pre-
catalyst oxygen sensors. Once the air pump is active and air
is injected into the system, the signal at the oxygen sensor
reflects a lean condition. If the oxygen sensor signal does not
change, a fault is set and the faulty
bank(s) identified. If after
completing the next cold startafault is again present, the MIL
illuminates.

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OBD-8
I On-Board Diagnostics
DTC digit interpretation
1st digit
P powertrain
B body
C chassis
2nd digit
0 SAE
1 BMW
3rd digit
0
1
2
3
4
5
6
7
4th - 5th digits total
system
airlfuei induction
fuel injection
ignition system or misfire
auxiliary emission control
vehicle speed
& idle control
ECM
inputs/outputs
transmission
individual circuits or
components
DTC example: P 0 3 0 6
P: A powertrain problem
0: SAE sanctioned or 'generic'
a 3: Related to an ignition system / misfire
06 Misfire detected at cylinder #6
DTCs provide a freeze frame or snap-shot of a vehicle
performance or emissions fault at the moment that the fault
first occurs. This information is accessible through generic
OED I1 scan tools.
Freeze frame data contains, but is not limited to, the following
information:
Engine load (calculated)
Engine rpm
Short and
long term fuel trim
Vehicle speed
Coolant temperature Intake manifold pressure
Open/closed loop operation
Fuel pressure (if available)
DTC