2001 BMW 540i air flow sensor

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.," --
Radiator and Cooling System --- 1
insert two M6 screws (arrows) in tapped bores and tighten
uniformly until pump is free from timing chain cover (thermo-
stat and hoses have been removed for purposes of visual
clarity).
Installation is reverse of removal, noting the following:
Be sure to replace sealing O-ring and gaskets.
Coat O-ring with water-based lubricant during installation.
Refill with coolant. See Coolant, draining and filling
(6-
cylinder models).
Tightening torques
-
Coolant pump to timing chain 10 Nm (89 in-lb)
cover
Coolant pump pulley to coolant
10 Nm (89 in-lb
pump
Engine block drain plug to block 25 Nm (1 8 It-lb)
Radiator drain plug to radiator 2 - 3 Nm (I8 - 27 in-lb)
Coolant pump, replacing (V-8 models)
I 1 < The engine coolant pump is mounted in the front of the en-
gine in ;he timing chain cover.
1. Thermostat housing
2. Thermostat
3. Thermostat sealing O-ring
4. Water pump
5. Water pump gasket
- Drain cooling system. See Coolant, draining and filling (V-
8 models).
- Remove cooling fan and fan shroud. See Mechanical (vis-
cous clutch) cooling fan, removing and installing.
- Remove engine drive belts: See 020 Maintenance.
NOTE-
Mark direction of drive belt rotation if reusing belt,
- Remove vibration dampener. See 117 Camshaft and Tim-
ing Chain.
- Disconnect mass air flow (MAF) sensor electrical harness
connector. Remove air intake duct together with
MAF sensor.
- Disconnect coolant hoses from thermostat housing and cool-
ant pump housing.

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.. - --
Radiator and Cooling System
Tightening torques
Coolant pump to timing chain 10
Nm (89 in-lb)
cover
Coolant pump
pulley to coolant
pump
10 Nm (89 in-lb
Engine
blocic drain plug to block 25 Nm (18 ft-lb)
Radiator drain plug to radiator
2-3Nm(18-27in-lb)
Thermostat cover to coolant
pump assembly 10 Nm (89 in-lb)
Radiator, removing and installing
Removal of the radiator is similar for V-8 and 6-cylinder mod-
els.
- Raise front of car and support safely.
WARNING -
Make sure the car is stable and well supported at aN times.
Use a professional automotive liff
orjaclc stands designed for
- Remove splash shield from under engine.
- Drain radiator and engine block. See Coolant, draining and
filling
(V-8 models).
WARNING -
Allow cooling system to cool before opening or draining sys-
tem.
< Remove air filter housing:
Disconnect electrical harness connectors
(A and B).
Loosen clamps (C and D).
Remove mounting fastener (arrow) and remove air filter
housing together with mass air flow
(MAF) sensor.

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OED-2
On-Board Diagnostics
Specialized OED II scan tool equipment is needed to access
the fault memory and
OED I1 data.
The extra hardware needed to operate the OED
I1 system
consists mainly of the following:
* Additional oxygen sensors downstream of the catalytic
converters.
Fuel tank pressure sensor and device to pressurize
fuel
storage system.
Several engine and performance monitoring devices
Standardized 16-pin
OED II connector under the
dashboard.
Upgraded components for the federally required reliability
mandate.
Malfunction indicator light (MIL)
OED II software illuminates the malfunction indicator light
(MIL) when emission levels exceed 1.5 times Federal
standards.
4 For E34 cars covered by this manual, three different MIL
symbols were used, depending on year and model.
MIL illuminates under the following conditions:
Engine management system fault detected for
two
consecutive OED iI drive cycles. See Drive cycle in this
repair group.
- Catalyst damaging fault detected.
Component malfunction causes emissions to exceed 1.5
times OED
II standards.
Manufacturer-defined specifications exceeded. Implausible input signal.
Misfire
faults.
Leak in evaporative system,
Oxygen sensors observe no purge
flow from purge valve 1
evaporative system.
ECM fails to enter closed-loop operation within specified
time.
ECM or automatic transmission control
module (TCM) in
"limp home" mode.
ignition key ON before cranking (bulb
check function).
OED
II fault memory (including the MIL) can only be reset
using a special scan tool. Removing the connector from the
ECM or disconnecting the battery does not erase the fault
memory.

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On-Board Diagnostics
l~utomatic transmission diagnostic trouble codes (continued)
P-code
1 Pi844
I I
14 /Pressure Control Solenoid 'D' Circuit Low
I I PI841 11 /Pressure Control Solenoid 'A' Circuit Low
BMW-FC
Pi842
I
P2722 15 I Pressure Control Solenoid 'E' I
DTC
Definition
Pi 845
Pi 882
Pi 883
PI 889
PI891
PI 892
PI 893
Pi 843 3 8
2 Pressure Control Solenoid '0' Circuit Low
5
57
58
96
96
96
83
P2729
P2730
P2759
P2761
P2763
P2764
Pressure Control Solenoid 'E' Circuit Low
2-3 Shift Circuit High
3-4 Shift Circuit High
System Voltage
- Electrical
System Voltage High Input
System Voltage Low Input
SUDP~V Voltaqe Pressure Control SoienoidIShift Solenoid Circuit High
~~ ~~ ~ Engine diagnostic trouble codes: M52 engine
5
5
4
4
4
4
I I
Pressure Control Solenoid 'E' Control Circuit Low
Pressure Control Solenoid
'E' Control Circuit High
Torque Converter Clutch Pressure Control
Solenoid Control Circuit Electrical
Torque Converter Clutch Pressure Control Solenoid Control
Circuitlopen
Torque Converter Clutch Pressure Control Solenoid Control Circuit High
Torque Converter Clutch Pressure Control Solenoid Control Circuit Low
DTC Definition
Mass or Volume Air
Flow Circuit RangeIPerformance
lntalte Air Temperature Sensor 1 Circuit Rangelperformance
Engine Coolant Temperature Circuit RangeIPerformance
ThrottieIPedai Position SensorISwitch 'A' Circuit
ThrottleIPedai Position SensorISwitch 'A' Circuit
P-code
PO1
01
PO1 11
PO116
PO120
PO120
PO1 20 BMW-FC
8 14
10
112
113
POI 20 1173 /~hrottie/~edal Position SensorISwitch 'A' Circuit
118
ThrottieIPedai Position SensorISwitch 'A' Circuit

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OBD-15
On-Board ~iagnosticsl
Engine diagnostic trouble codes: M52 engine (continued)
P-code
PO340
PO412
PO420
PO430
PO440
PO441
PO442
PO443
PO500
PO505
PO600
PO601
PO601
I PO601
~1132
~1133
BMW-FC
65
62
233
234
250 144
-
145
68
214
i I
DTC Definition
Camshalt Position Sensor 'A' Circuit (Bank 1 or Single Sensor)
Secondary Air Injection System Switching Valve A Circuit
Catalyst System Efficiency Below Threshold
(Bank 1)
Catalyst System Efficiency Below Threshold (Bank 2)
Evaporative Emission System
Eva~orative Emission Svstem Incorrect Purge Flow .
Evaporative Emission System Leak Detected (small leak)
Evaporative Emission System Purge Control Valve Circuit
Vehicle Speed Sensor 'A'
204
21 7
100
170
171
188
189
PI161
PI180
PI181
PI184
PI185
PI178
02 Sensor Heater Control Circuit (Bank 2 Sensor 2) I
idle Air Control System
Serial Communication
Link
Internal Control Module Memory Check Sum Error
Internal Control Module Memory
Check Sum Error
Internal Control Module Memory
Check Sum Error
02 Sensor Heater Control Circuit (Bank 1 Sensor
1)
02 Sensor Heater Control Circuit (Bank 2 Sensor 1)
Mass or Volume Air Flow Circuit RangeIPerlormance Problem PI140
I
I I
P1188 1227 I Fuel Control (Bank 1 Sensor 1)
PI145 150 /Solenoid Valve Running Losses Control Circuit Electrical
149
122
223
224
220 221
231
I I
P1189 1228 I Fuel Control (Banlc 2 Sensor 1)
Fuel Trim Adaptation Additive High (Bank 2) (M52: Engine Oil Temperature Sensor Circuit)
02 Sensor Signal Circuit Slow Switching from Rich to Lean
(Bank 1 Sensor 2)
02 Sensor Signal Circuit Slow Switching from Rich to Lean
(Bank 2 Sensor 2)
H02S Sensor Voltage Excursion Electrical (Banlc 1 Sensor 1)
HO2S Sensor Voltage Excursion Electrical (Banlc 2 Sensor 1)
02 Sensor Sianai Circuit Slow Switchina from Rich to Lean (Bank 1 Sensor 1)
02 Sensor Signal Circuit Slow Switching from Rich to Lean (Bank 2 Sensor 1) PI179
I I
PI190 1235 I Pre Catalyst Fuel Trim System (Banlc 1)
PI186 1190 102 Sensor Heater Control Circuit (Banlc 1 Sensor 2)
232
I I
PI191 1236 I Pre
Catalyst Fuel Trim System (Banlc 2)
PI192
. . -- - i Pi193 1226 I Post Catalvst Fuel Trim Svstem (Bank 2)
225
PI397
I I
Post Catalyst Fuel Trim System (Bank 1)
PI421 1246 /Secondarv Air System (Bank 2)
18
Secondary Air System (Bank
1) PI423
Camshaft Position Sensor '0' Circuit (Bank 1)
I 245

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On-Board ~iaanosticsl
Engine diagnostic trouble codes: M54 engine
P-code
BMW-FC Explanation
PO01 I / 103 I 'A' Camshaft Position Timing Over-Advanced or System Performance (Banlc 1) I I
PO012 1105 I 'A' Camshaft Position Timing Over-Retarded (Bank 1) I I
PO01 4 1104 I 'B' Camshaft Position Timing Over-Advanced or System Performance (Bank 1)
PO01 5
PO030
PO031
PO032
I 1
PO038 179 / HO2S Heater Control Circuit High (Bank 1 Sensor 2)
I I -.
I I
PO050 1 55 I H02S Heater Control Circuit (Bank 2 Sensor 1)
106
25
25
25
PO036
I I
PO051 1 55 I H02S Heater Control Circuit Low (Bank 2 Sensor 1)
'B' Camshaft Position Timing Over-Retarded (Bank 1)
H02S Heater Control Circuit (Bank 1 Sensor 1)
H02S Heater Control Circuit Low (Bank 1 Sensor 1)
H02S Heater Control Circuit Hiqh (Bank 1 Sensor 1)
PO037 1 79 I HO2S Heater Control Circuit Low (Bank 1 Sensor 2)
79
HOPS Heater
Control Circuit (Banlc 1 Sensor 2)
PO052
PO056
PO057
PO058
I I
PO1 03 / 8 I Mass or Volume Air Flow Circuit High. Input
I I -.
I I
PO1 07 1 197 I Manifold Absolute PressureIBarometric Pressure Circuit Low Input
55
61
61
61
PO101
I I
POI08 1197 / Manifold Absolute PressureIBarometric Pressure Circuit High Input
H02S Heater Control Circuit High (Bank 2 Sensor 1)
H02S Heater Control Circuit (Bank 2 Sensor 2)
HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
HO2S Heater Control Circuit Hiqh (Banlc 2 Sensor 2)
PO102 18 I Mass or Volume Air Flow Circuit Low Input
149
I I -
PO122 112 ThrottleIPedai Position SensorISwitch 'A' Circuit Low
PO123 1112 I ThrottleIPedal Position SensorISwitch 'A' Circuit High
Mass
or Volume Air Flow Circuit
RangeIPerformance
PO112
PO113
PO1 17
PO118
PO121
14
14
10
10
118
PO128
PO1 31
PO132
PO133
PO133
PO1 34 Intake
Air Temperature Sensor 1 Circuit Low
Intake Air Temperature Sensor 1 Circuit High
Engine Coolant Temperature Circuit Low
Engine Coolant Temperature Circuit High
ThrottleIPedal Position SensorISwitch 'A' Circuit RanqeIPerformance
I I
168
150
150
229
231
150
PO135
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
02 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
02 Sensor Circuit High Voltage (Bank 1 Sensor 1)
02 Sensor Circuit Slow Response (Bank
1 Sensor 1)
02 Sensor Circuit Slow Response
(Banlc 1 Sensor 1)
02 Sensor Circuit No Activitv Detected
(Banlc 1 Sensor 1)
188 02 Sensor Heater Circuit (Bank 1 Sensor 1)

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I On-Board Diagnostics
Engine diagnostic trouble codes: M54 engine (continued)
P-code
BMW-FC Explanation
Catalyst System Efficiency Below Threshold (Bank 2)
PO430
PO443
PO444
PO445
PO455
PO456
PO491
PO492
PO500
PO441 1250 / Evaporative Emission System Incorrect Purge Flow
234
I I
68
68
68 143
143
245
246
214
PO604
PI083
PI084
PI085
PI086
Evaporative Emission System Purge Control Valve Circuit
Evaporative Emission System Purge Control Valve Circuit Open
Evaporative Emission System Purge Control Valve Circuit Shorted
Evaporative Emission System Leak Detected (large leak)
Evaporative Emission System Leak Detected (very
small leak)
Secondary Air injection System Insufficient Flow (Bani( 1)
Secondary Air Injection System insufficient Flow
(Banic 2)
Vehicle Speed Sensor
'A'
Idle Air Control System PO505
.
PI 087
PI 088
PI089
PI090
PO600 / 217 I Serial Communication Link
204
100
202
202
203
203
PI091
PI092
PI093
PI094
Pllll
PI112
PI120
Internal Control Module Random Access Memory (RAM) Error
Fuel Control Limit Mixture Too Lean (Bank 1 Sensor
1)
Fuel Control Limit Mixture Too Rich (Bank 1 Sensor 1)
Fuel Control Limit Mixture Too Lean (Bank 2 Sensor 1)
Fuel Control Limit Mixture Too Rich (Banic 2 Sensor 1) ~ ~
229
229
230 235
PI121
PI122
PI123
02 Sensor Circuit Slow Response in Lean Control Range (Bank 1 Sensor 1)
02 Sensor Circuit Slow Response in Rich Control Range (Bank 1 Sensor
1)
02 Sensor Circuit Slow Response in Lean Control Range (Banlc 1 Sensor 2)
Pre Catalyst Fuel Trim System Too Lean
(Bank 1)
236
235
236
230
11
11
114
PI134
PI135
PI136
PI137
PI138
Pre Catalyst Fuel Trim System Too Lean (Banic 2)
Pre Catalyst Fuel Trim System Too Rich
(Bank 1)
Pre Catalyst Fuel Trim System Too Rich (Bank 2)
02 Sensor Circuit Slow Response in Rich Control Range (Banic 2 Sensor 1)
Engine Coolant Temperature Sensor Radiator Outlet Low Input
Engine Coolant Temperature Sensor Radiator Outlet High Input
Pedal Position Sensor Circuit
117
110
110
25
25
25
79
79 Pedal Position Sensor 1
RangeIPerformance Problem
Pedal Position Sensor 1 Low Input
Pedal Position Sensor 1 High Input
02 Sensor Heater Circuit Signal Intermittent (Bank 1 Sensor 1)
02 Sensor Heater Circuit Low Voltage (Bank 1 Sensor
1)
02 Sensor Heater Circuit High Voltage (Bank 1 Sensor 1)
02 Sensor Heater Circuit Signal Intermittent (Bank 1 Sensor 2)
02 Sensor Heater Circuit Low Voltage
(Banic 1 Sensor 2)
-
-

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/ On-Board Diaanostics I
Engine diagnostic trouble codes: M62 engine
P-code
PO01 1
PO012
PO020
PO021
PO022
PO030
PO031
PO032
I I
PO038 / 14 I H02S Heater Control Circuit High (Bank 1 Sensor 2)
PO010 / 33 / 'A' Camshaft Position Actuator Circuit (Bank 1)
BMW-FC
I I -.
Explanation
33
33
34
34
34 13
13
13
PO36
'A' Camshaft Position Timing Over-Advanced or System Performance (Bank 1)
'A' Camshaft Position Timing Over-Retarded (Bank 1)
'A' Camshaft Position Actuator Circuit (Bank 2)
'A' Camshaft Position Timing Over-Advanced or System Performance (Banlc 2)
'A' Camshaft Position Timing Over-Retarded (Banlc 2)
H02S Heater Control Circuit (Bank 1 Sensor 1)
H02S Heater Control Circuit Low (Bank 1 Sensor 1)
HOPS Heater Control Circuit Hiqh (Banlc 1 Sensor 1)
PO050
PO051
PO052
PO056
PO057
PO058
PO037 / 14 / H02S Heater Control Circuit Low (Bank 1 Sensor 2)
14
I I -.
Ir-1 ThrottleIPedal Position SensorISwitch 'A' Circuit
Low-
HO2S Heater Control Circuit (Bank 1 Sensor 2)
5
5
5
4
4
4
PO102
PO1 13
PO116
PO117
PO118
PO119
PO120
PO121
H02S Heater Control Circuit (Banlc 2 Sensor 1)
H02S Heater Control Circuit Low (Bank 2 Sensor 1)
H02S Heater Control Circuit High (Bank 2 Sensor 1)
H02S Heater Control Circuit (Bank 2 Sensor 2)
HO2S Heater Control Circuit Low (Bank 2 Sensor 2)
HO2S Heater Control Circuit Hiqh (Bank 2 Sensor 2)
PO103 1115 I Mass or Volume Air Flow Circuit High Input
115
124
123
123
123
123
117
118
PO1 23
PO125
PO128
PO1 30
PO131
POI 32
PO133
Mass or Volume Air Flow Circuit Low Input
lntalte Air Temperature Sensor 1 Circuit High
Engine Coolant Temperature Circuit
RangeIPerlormance
Engine Coolant Temperature Circuit Low
Engine Coolant Temperature Circuit High
Engine Coolant Temperature Circuit Intermittent
ThrottleIPedal Position SensorISwitch 'A' Circuit
ThrottieIPedal Position SensorISwitch 'A' Circuit RanqeIPerformance
118
123 139
10
10
10
15
ThrottleIPedai Position SensorlSwitch 'A' Circuit High
insufficient Coolant Temperature for Closed Loop Fuel Control
Coolant Thermostat (Coolant Temperature Below Thermostat Regulating Temperature)
02 Sensor Circuit (Bank
1 Sensor 1)
02 Sensor Circuit Low Voltage (Bank 1 Sensor 1)
02 Sensor Circuit High Voltage (Bank
1 Sensor 1)
02 Sensor Circuit Slow Response (Bank 1 Sensor
1)