Infiniti QX56 (Z62). Manual - part 637

EC-526

< SYMPTOM DIAGNOSIS >

[VK56VD]

ENGINE CONTROL SYSTEM SYMPTOMS

1 - 6: The numbers refer to the order of inspection.

(continued on next page)

SYSTEM — ENGINE MECHANICAL & OTHER

Manifold absolute pressure sensor circuit

3

EC-210

Battery current sensor

4

5

5

3

EC-412
EC-420
EC-424

Heated oxygen sensor 2

6

6

6

6

5

EC-243
EC-249
EC-257

SYMPTOM

Reference 
page

HARD/NO S

T

A

R

T/RES

T

A

R

T (E

XCP

. HA)

E

N

GINE

 ST

ALL

HES

IT

A

TION/SURGING/FLA

T

 SPOT

S

P

ARK KNOC

K

/DET

O

NA

TI

ON

LACK OF 

POWER/POOR ACCELERA

TION

HIG

H

 IDL

E

/L

OW

 ID

LE

ROUGH IDLE/HUNTING

ID

LING VI

BRA

T

ION

S

L

OW/NO RETU

RN 

T

O ID

LE

OVERHEA

T

S

/W

A

TER TEMPERA

T

URE HIG

H

E

XCESSIVE

 FUEL CON

S

UMP

T

ION

E

XCESSIVE

 OIL 

C

O

NSUMP

T

ION

B

A

TTER

Y 

DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG

AH

AJ

AK

AL

AM

HA

SYMPTOM

Reference 
page

HA

R

D

/N

O 

ST

A

R

T/RE

ST

A

R

T (E

XCP

. HA)

E

N

GI

N

E

 ST

ALL

HE

SIT

A

TION/SURGING/FLA

T

 SPOT

S

P

ARK

 KNOCK/DET

O

N

A

TI

ON

LACK OF 

POWER/POOR ACCELERA

TION

HIG

H

 I

D

L

E

/L

OW

 IDL

E

ROUGH IDLE/HUNTING

ID

LING VI

BRA

T

ION

SLOW/NO RETUR

N 

T

O

 IDLE

OVE

R

HE

A

T

S

/W

A

TER TE

MPERA

T

URE HIG

H

E

X

CESSIVE

 FUEL CONSUMP

T

ION

E

XCESSIVE

 OIL 

CONSUMP

T

ION

B

A

TTER

Y 

DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG

AH

AJ

AK

AL

AM

HA

Fuel

Fuel tank

5

5

FL-4

Fuel  piping

5

5

5

5

5

5

FL-4

Vapor lock

—

Valve deposit

5

5

5

5

5

5

5

—

Poor fuel (Heavy weight gasoline, 
Low octane)

—

ENGINE CONTROL SYSTEM SYMPTOMS

EC-527

< SYMPTOM DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

Air

Air duct

5

5

5

5

5

5

EM-28

Air cleaner

EM-27

Air leakage from air duct
(Mass air flow sensor — electric 
throttle control actuator)

5

5

5

5

EM-28

Electric throttle control actuator

EC-460

Air leakage from intake manifold/
Collector/Gasket

EM-30

Cranking

Battery

1

1

1

1

1

1

1

1

PG-161

Generator circuit

CHG-13

Starter circuit

3

STR-11

Signal plate

6

EM-106

PNP signal

4

EC-383

Engine

Cylinder head

5

5

5

5

5

5

5

5

EM-92

Cylinder head gasket

4

3

Cylinder block

6

6

6

6

6

6

6

6

4

EM-115

Piston

Piston ring

Connecting rod

Bearing

Crankshaft

Valve 
mecha-
nism

Timing chain

5

5

5

5

5

5

5

5

EM-72

Camshaft

EM-77

Intake valve timing control

EM-61

Intake valve

3

EM-92

Exhaust valve

Exhaust

Exhaust manifold/Tube/Muffler/
Gasket

5

5

5

5

5

5

5

5

EM-42
EX-6

Three way catalyst

SYMPTOM

Reference 
page

HARD/NO S

T

A

R

T/RES

T

A

R

T (E

XCP

. HA)

E

N

GINE

 ST

ALL

HES

IT

A

TION/SURGING/FLA

T

 SPOT

S

P

ARK KNOC

K

/DET

O

NA

TI

ON

LACK OF 

POWER/POOR ACCELERA

TION

HIG

H

 IDL

E

/L

OW

 ID

LE

ROUGH IDLE/HUNTING

ID

LING VI

BRA

T

ION

S

L

OW/NO RETU

RN 

T

O ID

LE

OVERHEA

T

S

/W

A

TER TEMPERA

T

URE HIG

H

E

XCESSIVE

 FUEL CON

S

UMP

T

ION

E

XCESSIVE

 OIL 

C

O

NSUMP

T

ION

B

A

TTER

Y 

DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG

AH

AJ

AK

AL

AM

HA

E C - 5 2 8

< SYMPTOM DIAGNOSIS >

[VK56VD]

ENGINE CONTROL SYSTEM SYMPTOMS

1 - 6: The numbers refer to the order of inspection.

Lubrica-
tion

Oil pan/Oil strainer/Oil pump/Oil 
filter/Oil gallery/Oil cooler

5

5

5

5

5

5

5

5

EM-56
EM-60
LU-9
LU-12
LU-14

Oil level (Low)/Filthy oil

LU-7

Cooling

Radiator/Hose/Radiator filler cap

5

5

5

5

5

5

5

4

5

CO-11
CO-11

Thermostat

5

CO-21

Water pump

CO-19

Water gallery

EM-115

Cooling fan

5

CO-17

Coolant level (Low)/Contaminat-
ed coolant

CO-8

IVIS (INFINITI Vehicle Immobilizer System — 
NATS)

1

1

SEC-48

SYMPTOM

Reference 
page

HARD/NO S

T

A

R

T/RES

T

A

R

T (E

XCP

. HA)

E

N

GINE

 ST

ALL

HES

IT

A

TION/SURGING/FLA

T

 SPOT

S

P

ARK KNOC

K

/DET

O

NA

TI

ON

LACK OF 

POWER/POOR ACCELERA

TION

HIG

H

 IDL

E

/L

OW

 ID

LE

ROUGH IDLE/HUNTING

ID

LING VI

BRA

T

ION

S

L

OW/NO RETU

RN 

T

O ID

LE

OVERHEA

T

S

/W

A

TER TEMPERA

T

URE HIG

H

E

XCESSIVE

 FUEL CON

S

UMP

T

ION

E

XCESSIVE

 OIL 

C

O

NSUMP

T

ION

B

A

TTER

Y 

DEAD (UNDER CHARGE)

Warranty symptom code

AA

AB

AC

AD

AE

AF

AG

AH

AJ

AK

AL

AM

HA

NORMAL OPERATING CONDITION

EC-529

< SYMPTOM DIAGNOSIS >

[VK56VD]

C

D

E

F

G

H

I

J

K

L

M

A

EC

N

P

O

NORMAL OPERATING CONDITION

Description

INFOID:0000000006218029

FUEL CUT CONTROL (AT NO LOAD AND HIGH ENGINE SPEED)

If the engine speed is above 1,800 rpm under no load (for example, the selector lever position is neutral and
engine speed is over 1,800 rpm) fuel will be cut off after some time. The exact time when the fuel is cut off var-
ies based on engine speed.
Fuel cut will be operated until the engine speed reaches 1,500 rpm, then fuel cut will be cancelled.
NOTE:
This function is different from deceleration control listed under direct injection gasoline System, 

EC-36,

"DIRECT INJECTION GASOLINE SYSTEM : System Description"

.