2001 INFINITI QX4 coolant temperature

SAT014K
If the DTC is being detected currently, the time data will be ª0º.
SAT015K
If a 1st trip DTC is stored in the ECM, the time data will be ª1tº.
SAT016K
Freeze Frame Data and 1st Trip Freeze Frame DataNBAT0016S0101The ECM has a memory function, which stores the driving condition such as fuel system status, calculated
load value, engine coolant temperature, short term fuel trim, long term fuel trim, engine speed and vehicle
speed at the moment the ECM detects a malfunction.
Data which are stored in the ECM memory, along with the 1st trip DTC, are called 1st trip freeze frame data,
and the data, stored together with the DTC data, are called freeze frame data and displayed on CONSULT-II
or GST. The 1st trip freeze frame data can only be displayed on the CONSULT-II screen, not on the GST. For
detail, refer to EC-81, ªCONSULT-IIº.
Only one set of freeze frame data (either 1st trip freeze frame data of freeze frame data) can be stored in the
ECM. 1st trip freeze frame data is stored in the ECM memory along with the 1st trip DTC. There is no prior-
ity for 1st trip freeze frame data and it is updated each time a different 1st trip DTC is detected. However, once
freeze frame data (2nd trip detection/MIL on) is stored in the ECM memory, 1st trip freeze frame data is no
longer stored. Remember, only one set of freeze frame data can be stored in the ECM. The ECM has the fol-
lowing priorities to update the data.
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTION
OBD-II Diagnostic Trouble Code (DTC) (Cont'd)
AT-34

CONSULT-II Reference Value in Data Monitor
Mode ........................................................................150
ECM Terminals and Reference Value .....................150
On Board Diagnosis Logic.......................................151
Possible Cause ........................................................151
DTC Confirmation Procedure ..................................151
Overall Function Check ...........................................153
Wiring Diagram ........................................................154
Diagnostic Procedure ..............................................155
DTC P0105 ABSOLUTE PRESSURE SENSOR........158
Component Description ...........................................158
ECM Terminals and Reference Value .....................158
On Board Diagnosis Logic.......................................158
Possible Cause ........................................................159
DTC Confirmation Procedure ..................................159
Wiring Diagram ........................................................160
Diagnostic Procedure ..............................................161
DTC P0110 INTAKE AIR TEMPERATURE
SENSOR......................................................................164
Component Description ...........................................164
On Board Diagnosis Logic.......................................164
Possible Cause ........................................................164
DTC Confirmation Procedure ..................................164
Wiring Diagram ........................................................166
Diagnostic Procedure ..............................................167
DTC P0115 ENGINE COOLANT TEMPERATURE
SENSOR (ECTS) (CIRCUIT).......................................169
Component Description ...........................................169
On Board Diagnosis Logic.......................................169
Possible Cause ........................................................170
DTC Confirmation Procedure ..................................170
Wiring Diagram ........................................................171
Diagnostic Procedure ..............................................172
DTC P0120 THROTTLE POSITION SENSOR...........174
Description ...............................................................174
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................174
ECM Terminals and Reference Value .....................175
On Board Diagnosis Logic.......................................175
Possible Cause ........................................................175
DTC Confirmation Procedure ..................................176
Wiring Diagram ........................................................180
Diagnostic Procedure ..............................................181
DTC P0125 ENGINE COOLANT TEMPERATURE
SENSOR (ECTS).........................................................187
Description ...............................................................187
On Board Diagnosis Logic.......................................187
Possible Cause ........................................................188
DTC Confirmation Procedure ..................................188
Wiring Diagram ........................................................189
Diagnostic Procedure ..............................................190DTC P0130, P0150 HEATED OXYGEN SENSOR 1
(FRONT) (BANK 1)/(BANK 2) (CIRCUIT)..................192
Component Description ...........................................192
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................192
ECM Terminals and Reference Value .....................192
On Board Diagnosis Logic.......................................193
Possible Cause ........................................................193
DTC Confirmation Procedure ..................................194
Overall Function Check ...........................................194
Wiring Diagram ........................................................196
Diagnostic Procedure ..............................................198
DTC P0131, P0151 HEATED OXYGEN SENSOR 1
(FRONT) (BANK 1)/(BANK 2) (LEAN SHIFT
MONITORING).............................................................202
Component Description ...........................................202
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................202
ECM Terminals and Reference Value .....................202
On Board Diagnosis Logic.......................................203
Possible Cause ........................................................203
DTC Confirmation Procedure ..................................203
Overall Function Check ...........................................204
Diagnostic Procedure ..............................................205
DTC P0132, P0152 HEATED OXYGEN SENSOR 1
(FRONT) (BANK 1)/(BANK 2) (RICH SHIFT
MONITORING).............................................................210
Component Description ...........................................210
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................210
ECM Terminals and Reference Value .....................210
On Board Diagnosis Logic....................................... 211
Possible Cause ........................................................ 211
DTC Confirmation Procedure .................................. 211
Overall Function Check ...........................................212
Diagnostic Procedure ..............................................213
DTC P0133, P0153 HEATED OXYGEN SENSOR 1
(FRONT) (BANK 1)/(BANK 2) (RESPONSE
MONITORING).............................................................218
Component Description ...........................................218
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................218
ECM Terminals and Reference Value .....................218
On Board Diagnosis Logic.......................................219
Possible Cause ........................................................219
DTC Confirmation Procedure ..................................220
Overall Function Check ...........................................221
Wiring Diagram ........................................................222
Diagnostic Procedure ..............................................224
DTC P0134, P0154 HEATED OXYGEN SENSOR 1
(FRONT) (BANK 1)/(BANK 2) (HIGH VOLTAGE)......231
Component Description ...........................................231
CONTENTS(Cont'd)
EC-2

DTC P0217 COOLANT OVERTEMPERATURE
ENRICHMENT PROTECTION.....................................314
On Board Diagnosis Logic.......................................314
Possible Cause ........................................................314
Overall Function Check ...........................................314
Diagnostic Procedure ..............................................316
Main 12 Causes of Overheating..............................319
DTC P0300 - P0306 NO.6-1CYLINDER
MISFIRE, MULTIPLE CYLINDER MISFIRE...............320
On Board Diagnosis Logic.......................................320
Possible Cause ........................................................320
DTC Confirmation Procedure ..................................321
Diagnostic Procedure ..............................................321
DTC P0325 KNOCK SENSOR (KS)...........................328
Component Description ...........................................328
ECM Terminals and Reference Value .....................328
On Board Diagnosis Logic.......................................328
Possible Cause ........................................................328
DTC Confirmation Procedure ..................................328
Wiring Diagram ........................................................330
Diagnostic Procedure ..............................................331
DTC P0335 CRANKSHAFT POSITION SENSOR
(CKPS) (POS)..............................................................334
Component Description ...........................................334
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................334
ECM Terminals and Reference Value .....................335
On Board Diagnosis Logic.......................................335
Possible Cause ........................................................335
DTC Confirmation Procedure ..................................336
Wiring Diagram ........................................................337
Diagnostic Procedure ..............................................338
DTC P0340 CAMSHAFT POSITION SENSOR
(CMPS) (PHASE).........................................................342
Component Description ...........................................342
ECM Terminals and Reference Value .....................342
On Board Diagnosis Logic.......................................342
Possible Cause ........................................................343
DTC Confirmation Procedure ..................................343
Wiring Diagram ........................................................344
Diagnostic Procedure ..............................................345
DTC P0420 (RIGHT BANK, -B1), P0430 (LEFT
BANK, -B2) THREE WAY CATALYST FUNCTION...347
On Board Diagnosis Logic.......................................347
Possible Cause ........................................................347
DTC Confirmation Procedure ..................................348
Overall Function Check ...........................................348
Diagnostic Procedure ..............................................349
DTC P0440 EVAP CONTROL SYSTEM (SMALL
LEAK) (NEGATIVE PRESSURE)................................352
On Board Diagnosis Logic.......................................352
Possible Cause ........................................................352DTC Confirmation Procedure ..................................354
Diagnostic Procedure ..............................................355
DTC P0443 EVAP CANISTER PURGE VOLUME
CONTROL SOLENOID VALVE (CIRCUIT).................367
Description ...............................................................367
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................367
ECM Terminals and Reference Value .....................368
On Board Diagnosis Logic.......................................368
Possible Cause ........................................................368
DTC Confirmation Procedure ..................................369
Wiring Diagram ........................................................370
Diagnostic Procedure ..............................................371
DTC P0446 EVAPORATIVE EMISSION (EVAP)
CANISTER VENT CONTROL VALVE (CIRCUIT)......374
Component Description ...........................................374
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................374
ECM Terminals and Reference Value .....................374
On Board Diagnosis Logic.......................................374
Possible Cause ........................................................375
DTC Confirmation Procedure ..................................375
Wiring Diagram ........................................................376
Diagnostic Procedure ..............................................377
DTC P0450 EVAPORATIVE EMISSION (EVAP)
CONTROL SYSTEM PRESSURE SENSOR..............381
Component Description ...........................................381
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................381
ECM Terminals and Reference Value .....................381
On Board Diagnosis Logic.......................................382
Possible Cause ........................................................382
DTC Confirmation Procedure ..................................382
Wiring Diagram ........................................................384
Diagnostic Procedure ..............................................385
DTC P0455 EVAP CONTROL SYSTEM (GROSS
LEAK)...........................................................................394
On Board Diagnosis Logic.......................................394
Possible Cause ........................................................394
DTC Confirmation Procedure ..................................396
Diagnostic Procedure ..............................................397
DTC P0460 FUEL LEVEL SENSOR FUNCTION
(SLOSH).......................................................................407
Component Description ...........................................407
On Board Diagnostic Logic......................................407
Possible Cause ........................................................407
DTC Confirmation Procedure ..................................407
Wiring Diagram ........................................................408
Diagnostic Procedure ..............................................409
DTC P0461 FUEL LEVEL SENSOR FUNCTION....... 411
Component Description ........................................... 411
On Board Diagnostic Logic...................................... 411
CONTENTS(Cont'd)
EC-4

CONSULT-II Reference Value in Data Monitor
Mode ........................................................................585
ECM Terminals and Reference Value .....................585
On Board Diagnosis Logic.......................................586
Possible Cause ........................................................586
DTC Confirmation Procedure ..................................586
Wiring Diagram ........................................................587
Diagnostic Procedure ..............................................588
DTC P1491 VACUUM CUT VALVE BYPASS
VALVE..........................................................................591
Description ...............................................................591
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................591
ECM Terminals and Reference Value .....................591
On Board Diagnosis Logic.......................................592
Possible Cause ........................................................592
DTC Confirmation Procedure ..................................592
Overall Function Check ...........................................593
Wiring Diagram ........................................................594
Diagnostic Procedure ..............................................595
DTC P1605 A/T DIAGNOSIS COMMUNICATION
LINE.............................................................................603
Component Description ...........................................603
On Board Diagnosis Logic.......................................603
Possible Cause ........................................................603
DTC Confirmation Procedure ..................................603
DTC P1706 PARK/NEUTRAL POSITION (PNP)
SWITCH.......................................................................604
Component Description ...........................................604
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................604
ECM Terminals and Reference Value .....................604
On Board Diagnosis Logic.......................................604
Possible Cause ........................................................604
DTC Confirmation Procedure ..................................605
Overall Function Check ...........................................606
Wiring Diagram ........................................................607
Diagnostic Procedure ..............................................608
VARIABLE INDUCTION AIR CONTROL SYSTEM
(VIAS)...........................................................................610
Description ...............................................................610
ECM Terminals and Reference Value ..................... 611
Wiring Diagram ........................................................612
Diagnostic Procedure ..............................................613
INJECTOR...................................................................616
Component Description ...........................................616
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................616
ECM Terminals and Reference Value .....................616
Wiring Diagram ........................................................617Diagnostic Procedure ..............................................618
START SIGNAL...........................................................621
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................621
ECM Terminals and Reference Value .....................621
Wiring Diagram ........................................................622
Diagnostic Procedure ..............................................623
FUEL PUMP.................................................................625
System Description ..................................................625
Component Description ...........................................625
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................625
ECM Terminals and Reference Value .....................626
Wiring Diagram ........................................................627
Diagnostic Procedure ..............................................628
POWER STEERING OIL PRESSURE SWITCH.........634
Component Description ...........................................634
CONSULT-II Reference Value in Data Monitor
Mode ........................................................................634
ECM Terminals and Reference Value .....................634
Wiring Diagram ........................................................635
Diagnostic Procedure ..............................................636
REFRIGERANT PRESSURE SENSOR......................639
Description ...............................................................639
ECM Terminals and Reference Value .....................639
Wiring Diagram ........................................................640
Diagnostic Procedure ..............................................641
ELECTRICAL LOAD SIGNAL.....................................643
ECM Terminals and Reference Value .....................643
Wiring Diagram ........................................................644
Diagnostic Procedure ..............................................645
MIL & DATA LINK CONNECTORS............................648
Wiring Diagram ........................................................648
SERVICE DATA AND SPECIFICATIONS (SDS).......649
Fuel Pressure Regulator..........................................649
Idle Speed and Ignition Timing ................................649
Mass Air Flow Sensor..............................................649
Engine Coolant Temperature Sensor ......................649
Heated Oxygen Sensor 1 Heater (Front) ................649
Fuel Pump ...............................................................649
IACV-AAC Valve ......................................................649
Injector .....................................................................649
Resistor ....................................................................649
Throttle Position Sensor ..........................................650
Calculated Load Value.............................................650
Intake Air Temperature Sensor ................................650
Heated Oxygen Sensor 2 Heater (Rear).................650
Crankshaft Position Sensor (REF) ..........................650
Fuel Tank Temperature Sensor ...............................650
Camshaft Position Sensor (PHASE) .......................650GI
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CONTENTS(Cont'd)
EC-7

System ChartNBEC0013
Input (Sensor) ECM Function Output (Actuator)
ICamshaft position sensor (PHASE)
ICrankshaft position sensor (REF)
IMass air flow sensor
IEngine coolant temperature sensor
IHeated oxygen sensor 1 (front)
IIgnition switch
IThrottle position sensor
IClosed throttle position switch*3
IPark/neutral position (PNP) switch
IAir conditioner switch
IKnock sensor
IIntake air temperature sensor
IAbsolute pressure sensor
IEVAP control system pressure sensor*1
IBattery voltage
IPower steering oil pressure switch
IVehicle speed sensor
IFuel tank temperature sensor*1
ICrankshaft position sensor (POS)
IHeated oxygen sensor 2 (rear)*2
ITCM (Transmission control module)
IRefrigerant pressure sensor
IElectrical load
IFuel level sensor*1Fuel injection & mixture ratio control Injectors
Electronic ignition system Power transistor
Idle air control system IACV-AAC valve
Fuel pump control Fuel pump relay
On board diagnostic system MIL (On the instrument panel)
Swirl control valve controlSwirl control valve control solenoid
valve
Power valve control VIAS control solenoid valve
Heated oxygen sensor 1 heater (front) con-
trolHeated oxygen sensor 1 heater
(front)
Heated oxygen sensor 2 heater (rear) controlHeated oxygen sensor 2 heater
(rear)
EVAP canister purge flow controlEVAP canister purge volume con-
trol solenoid valve
Air conditioning cut control Air conditioner relay
ON BOARD DIAGNOSIS for EVAP systemIEVAP canister vent control valve
IVacuum cut valve bypass valve
*1: These sensors are not used to control the engine system. They are used only for the on board diagnosis.
*2: This sensor is not used to control the engine system under normal conditions.
*3: This switch will operate in place of the throttle position sensor to control EVAP parts if the sensor malfunctions.GI
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ENGINE AND EMISSION CONTROL OVERALL SYSTEM
System Chart
EC-27

Multiport Fuel Injection (MFI) System
DESCRIPTIONNBEC0014Input/Output Signal ChartNBEC0014S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed (POS signal)
Fuel injec-
tion & mix-
ture ratio
controlInjectors Crankshaft position sensor (REF) Engine speed (REF signal)
Camshaft position sensor (PHASE) Piston position
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Heated oxygen sensor 1 (front) Density of oxygen in exhaust gas
Throttle position sensorThrottle position
Throttle valve idle position
Park/neutral position (PNP) switch Gear position
Vehicle speed sensor Vehicle speed
Ignition switch Start signal
Air conditioner switch Air conditioner operation
Knock sensor Engine knocking condition
Battery Battery voltage
Absolute pressure sensor Ambient air barometric pressure
Power steering oil pressure switch Power steering operation
Heated oxygen sensor 2 (rear)* Density of oxygen in exhaust gas
*: Under normal conditions, this sensor is not for engine control operation.
Basic Multiport Fuel Injection SystemNBEC0014S02The amount of fuel injected from the fuel injector is determined by the ECM. The ECM controls the length of
time the valve remains open (injection pulse duration). The amount of fuel injected is a program value in the
ECM memory. The program value is preset by engine operating conditions. These conditions are determined
by input signals (for engine speed and intake air) from both the crankshaft position sensor and the mass air
flow sensor.
Various Fuel Injection Increase/Decrease CompensationNBEC0014S03In addition, the amount of fuel injected is compensated to improve engine performance under various oper-
ating conditions as listed below.

IDuring warm-up
IWhen starting the engine
IDuring acceleration
IHot-engine operation
IWhen selector lever is changed from ªNº to ªDº
IHigh-load, high-speed operation

IDuring deceleration
IDuring high engine speed operation
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System
EC-28

Mixture Ratio Feedback Control (Closed loop control)NBEC0014S04
SEF336WA
The mixture ratio feedback system provides the best air-fuel mixture ratio for driveability and emission con-
trol. The warm-up three way catalyst can then better reduce CO, HC and NOx emissions. This system uses
a heated oxygen sensor 1 (front) in the exhaust manifold to monitor if the engine operation is rich or lean. The
ECM adjusts the injection pulse width according to the sensor voltage signal. For more information about the
heated oxygen sensor 1 (front), refer to EC-192. This maintains the mixture ratio within the range of stoichio-
metric (ideal air-fuel mixture).
This stage is referred to as the closed loop control condition.
Heated oxygen sensor 2 (rear) is located downstream of the warm-up three way catalyst. Even if the switch-
ing characteristics of the heated oxygen sensor 1 (front) shift, the air-fuel ratio is controlled to stoichiometric
by the signal from the heated oxygen sensor 2 (rear).
Open Loop ControlNBEC0014S05The open loop system condition refers to when the ECM detects any of the following conditions. Feedback
control stops in order to maintain stabilized fuel combustion.
IDeceleration and acceleration
IHigh-load, high-speed operation
IMalfunction of heated oxygen sensor 1 (front) or its circuit
IInsufficient activation of heated oxygen sensor 1 (front) at low engine coolant temperature
IHigh engine coolant temperature
IDuring warm-up
IAfter shifting from ªNº to ªDº
IWhen starting the engine
Mixture Ratio Self-learning ControlNBEC0014S06The mixture ratio feedback control system monitors the mixture ratio signal transmitted from the heated oxy-
gen sensor 1 (front). This feedback signal is then sent to the ECM. The ECM controls the basic mixture ratio
as close to the theoretical mixture ratio as possible. However, the basic mixture ratio is not necessarily con-
trolled as originally designed. Both manufacturing differences (i.e., mass air flow sensor hot wire) and char-
acteristic changes during operation (i.e., injector clogging) directly affect mixture ratio.
Accordingly, the difference between the basic and theoretical mixture ratios is monitored in this system. This
is then computed in terms of ªinjection pulse durationº to automatically compensate for the difference between
the two ratios.
ªFuel trimº refers to the feedback compensation value compared against the basic injection duration. Fuel trim
includes short term fuel trim and long term fuel trim.
ªShort term fuel trimº is the short-term fuel compensation used to maintain the mixture ratio at its theoretical
value. The signal from the heated oxygen sensor 1 (front) indicates whether the mixture ratio is RICH or LEAN
compared to the theoretical value. The signal then triggers a reduction in fuel volume if the mixture ratio is
rich, and an increase in fuel volume if it is lean.
ªLong term fuel trimº is overall fuel compensation carried out long-term to compensate for continual deviation
of the short term fuel trim from the central value. Such deviation will occur due to individual engine differences,
wear over time and changes in the usage environment.
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ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System (Cont'd)
EC-29

Fuel Injection TimingNBEC0014S07
SEF179U
Two types of systems are used.
Sequential Multiport Fuel Injection System
NBEC0014S0701Fuel is injected into each cylinder during each engine cycle according to the firing order. This system is used
when the engine is running.
Simultaneous Multiport Fuel Injection System
NBEC0014S0702Fuel is injected simultaneously into all six cylinders twice each engine cycle. In other words, pulse signals of
the same width are simultaneously transmitted from the ECM.
The six injectors will then receive the signals two times for each engine cycle.
This system is used when the engine is being started and/or if the fail-safe system (CPU) is operating.
Fuel Shut-offNBEC0014S08Fuel to each cylinder is cut off during deceleration or operation of the engine at excessively high speeds.
Electronic Ignition (EI) System
DESCRIPTIONNBEC0015Input/Output Signal ChartNBEC0015S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor (POS) Engine speed (POS signal)
Ignition
timing con-
trolPower transistor Crankshaft position sensor (REF) Engine speed (REF signal)
Camshaft position sensor (PHASE) Piston position
Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Throttle position sensorThrottle position
Throttle valve idle position
Vehicle speed sensor Vehicle speed
Ignition switch Start signal
Knock sensor Engine knocking
Park/neutral position (PNP) switch Gear position
Battery Battery voltage
ENGINE AND EMISSION BASIC CONTROL SYSTEM DESCRIPTION
Multiport Fuel Injection (MFI) System (Cont'd)
EC-30