On Board Diagnosis LogicNCEC0188With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the Heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too lean.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0171
0171IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too lean.)IIntake air leaks
IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
ILack of fuel
IMass air flow sensor
DTC Confirmation ProcedureNCEC0189NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARNING CONTº
in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0171 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-QG-
211.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-QG-211. If engine
does not start, visually check for exhaust and intake air leak.
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
SEF652Y
NEF068A
SEF995W
DTC P0171 FUEL INJECTION SYSTEM FUNCTION
(LEAN SIDE)QG16I18DE
On Board Diagnosis Logic
EC-208
On Board Diagnosis LogicNCEC0192With the Air/Fuel Mixture Ratio Self-Learning Control, the actual mixture ratio can be brought closely to the
theoretical mixture ratio based on the mixture ratio feedback signal from the Heated oxygen sensor 1 (front).
The ECM calculates the necessary compensation to correct the offset between the actual and the theoretical
ratios.
In case the amount of the compensation value is extremely large (The actual mixture ratio is too rich.), the
ECM judges the condition as the fuel injection system malfunction and lights up the MI (2 trip detection logic).
Sensor Input Signal to ECMECM func-
tionActuator
Heated oxygen sensor 1 (front)Density of oxygen in exhaust gas
(Mixture ratio feedback signal)Fuel injec-
tion & mix-
ture ratio
controlInjectors
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0172
0172IFuel injection system does not operate properly.
IThe amount of mixture ratio compensation is too large.
(The mixture ratio is too rich.)IHeated oxygen sensor 1 (front)
IInjectors
IExhaust gas leaks
IIncorrect fuel pressure
IMass air flow sensor
DTC Confirmation ProcedureNCEC0193NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Turn ignition switch ªONº and select ªSELF-LEARN CON-
TROLº in ªWORK SUPPORTº mode with CONSULT-II.
4) Clear the self-learning control coefficient by touching ªCLEARº.
5) Select ªDATA MONITORº mode with CONSULT-II.
6) Start engine again and let it idle for at least 10 minutes.
The 1st trip DTC P0172 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº, EC-QG-
218.
7) If it is difficult to start engine at step 6, the fuel injection sys-
tem has a malfunction.
8) Crank engine while depressing accelerator pedal. If engine
starts, go to ªDiagnostic Procedureº, EC-QG-218. If engine
does not start, remove ignition plugs and check for fouling, etc.
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch ªOFFº and wait at least 9 seconds.
3) Disconnect mass air flow sensor harness connector. Then
restart and run engine for at least 3 seconds at idle speed.
4) Stop engine and reconnect mass air flow sensor harness con-
nector.
5) Select ªMODE 7º with GST. Make sure 1st trip DTC P0100 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0100.
SEF652Y
NEF068A
SEF995W
DTC P0172 FUEL INJECTION SYSTEM FUNCTION
(RICH SIDE)QG16I18DE
On Board Diagnosis Logic
EC-215
On Board Diagnosis LogicNCEC0202When a misfire occurs, the engine speed will fluctuate. If the engine speed fluctuates enough to cause the
CKP sensor signal to vary, The ECM can determine that a misfire is occurring.
Sensor Input Signal to ECM ECM function
Crankshaft position sensor (POS) Engine speed On board diagnosis of misfire
The misfire detection logic consists of the following two conditions.
1. One Trip Detection Logic (Three Way Catalyst Damage)
On the first trip that a misfire condition occurs that can damage the three way catalyst (TWC) due to
overheating, the MI will blink.
When a misfire condition occurs, the ECM monitors the CKP sensor signal every 200 engine revolutions
for a change.
When the misfire condition decreases to a level that will not damage the TWC, the MI will turn off.
If another misfire condition occurs that can damage the TWC on a second trip, the MI will blink.
When the misfire condition decreases to a level that will not damage the TWC, the MI will remain on.
If another misfire condition occurs that can damage the TWC, the MI will begin to blink again.
(After the first trip detection, the MI will light up from engine starting. If a misfire is detected that will cause
three way catalyst damage, the MI will start blinking.)
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect emissions), the MI will only light when
the misfire is detected on a second trip. During this condition, the ECM monitors the CKP sensor signal
every 1,000 engine revolutions.
A misfire malfunction can be detected on any one cylinder or on multiple cylinders.
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0300
0300IMultiple cylinders misfire.IImproper spark plug
IInsufficient compression
IIncorrect fuel pressure
IEGR volume control valve (If so equipped)
IThe injector circuit is open or shorted
IInjectors
IIntake air leak
IInsufficient ignition spark
ILack of fuel
IHeated oxygen sensor 1 (front) P0301
0301INo. 1 cylinder misfires.
P0302
0302INo. 2 cylinder misfires.
P0303
0303INo. 3 cylinder misfires.
P0304
0304INo. 4 cylinder misfires.
DTC Confirmation ProcedureNCEC0203CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
With CONSULT-II
1) Turn ignition switch ªONº, and select ªDATA MONITORº mode
with CONSULT-II.
NEF068A
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE,
MULTIPLE CYLINDER MISFIREQG16I18DE
On Board Diagnosis Logic
EC-222
Component DescriptionNCEC0206The knock sensor is attached to the cylinder block. It senses
engine knocking using a piezoelectric element. A knocking vibration
from the cylinder block is sensed as vibrational pressure. This
pressure is converted into a voltage signal and sent to the ECM.
Freeze frame data will not be stored in the ECM for the knock
sensor. The MI will not light for knock sensor malfunction. The
knock sensor has one trip detection logic.
ECM Terminals and Reference ValueNCEC0207Specification data are reference values and are measured between each terminal and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/output voltage. Doing so may result in dam-
age to the ECM's transistor. Use a ground other than ECM terminals, such as the ground.
TERMI-
NAL
NO.WIRE
COLORITEM CONDITION DATA (DC Voltage)
81 W Knock sensor[Engine is running]
IIdle speed1.0 - 4.0V
On Board Diagnosis LogicNCEC0208
DTC No. Malfunction is detected when ... Check Items (Possible Cause)
P0325
0325IAn excessively low or high voltage from the knock sen-
sor is sent to ECM.IHarness or connectors
(The knock sensor circuit is open or shorted.)
IKnock sensor
DTC Confirmation ProcedureNCEC0209NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch ªOFFº and wait at least 9 seconds
before conducting the next test.
TESTING CONDITION:
Before performing the following procedure, confirm that bat-
tery voltage is more than 10V at idle.
With CONSULT-II
1) Turn ignition switch ªONº and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine and run it for at least 5 seconds at idle speed.
3) If DTC is detected, go to ªDiagnostic Procedureº, EC-QG-230.
With GST
Follow the procedure ªWith CONSULT-IIº above.
SEF598K
NEF068A
DTC P0325 KNOCK SENSOR (KS)QG16I18DE
Component Description
EC-228
DescriptionNCEC0227SYSTEM DESCRIPTIONNCEC0227S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor Engine speed
EGR control EGR volume control valve Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
Battery Battery voltage
This system controls flow rate of EGR led from exhaust manifold
to intake manifold. The opening of the EGR by-pass passage in the
EGR volume control valve changes to control the flow rate. A
built-in step motor moves the valve in steps corresponding to the
ECM output pulses. The opening of the valve varies for optimum
engine control. The optimum value stored in the ECM is determined
by considering various engine conditions. The EGR volume control
valve remains closed under the following conditions.
ILow engine coolant temperature
IEngine starting
IHigh-speed engine operation
IExtremely light load engine operation
IEngine idling
IExcessively high engine coolant temperature
IWide open throttle
IMass air flow sensor malfunction
ILow battery voltage
COMPONENT DESCRIPTIONNCEC0227S02EGR Volume Control ValveNCEC0227S0201The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the
ECM. Two windings are turned ON and OFF in sequence. Each
time an ON pulse is issued, the valve opens or closes, changing
the flow rate. When no change in the flow rate is needed, the ECM
does not issue the pulse signal. A certain voltage signal is issued
so that the valve remains at that particular opening.
SEF551W
SEF552W
DTC P0400 EGR FUNCTION (CLOSE) (IF SO EQUIPPED)QG16I18DE
Description
EC-244
DescriptionNCEC0504SYSTEM DESCRIPTIONNCEC0504S01
Sensor Input Signal to ECMECM func-
tionActuator
Crankshaft position sensor Engine speed
EGR control EGR volume control valve Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
Battery Battery voltage
This system controls flow rate of EGR led from exhaust manifold
to intake manifold. The opening of the EGR by-pass passage in the
EGR volume control valve changes to control the flow rate. A
built-in step motor moves the valve in steps corresponding to the
ECM output pulses. The opening of the valve varies for optimum
engine control. The optimum value stored in the ECM is determined
by considering various engine conditions. The EGR volume control
valve remains closed under the following conditions.
ILow engine coolant temperature
IEngine starting
IHigh-speed engine operation
IExtremely light load engine operation
IEngine idling
IExcessively high engine coolant temperature
IWide open throttle
IMass air flow sensor malfunction
ILow battery voltage
COMPONENT DESCRIPTIONNCEC0504S02The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the
ECM. Two windings are turned ON and OFF in sequence. Each
time an ON pulse is issued, the valve opens or closes, changing
the flow rate. When no change in the flow rate is needed, the ECM
does not issue the pulse signal. A certain voltage signal is issued
so that the valve remains at that particular opening.
SEF551W
SEF552W
DTC P0403 EGR VOLUME CONTROL VALVE (CIRCUIT)
(IF SO EQUIPPED)QG16I18DE
Description
EC-252
4 CHECK AIR CONTROL VALVE (POWER STEERING) OPERATION-I
1. Reconnect the ECM harness connector and IACV-AAC valve harness connector.
2. Disconnect the vacuum hose connected to the air control valve (Power steering) at the intake air duct.
3. Start engine and let it idle.
4. Check vacuum hose for vacuum existence.
SEF162Z
Vacuum does not exist or slightly exist.
OK or NG
OK©GO TO 5.
NG©Replace air control valve (Power steering).
5 CHECK AIR CONTROL VALVE (POWER STEERING) OPERATION-II
Check the vacuum hose for vacuum existence when steering wheel is turned.
SEF162Z
Vacuum should exist.
OK or NG
OK©GO TO 8.
NG©GO TO 6.
DTC P0505 IDLE AIR CONTROL VALVE (IACV) Ð
AUXILIARY AIR CONTROL (AAC) VALVEQG16I18DE
Diagnostic Procedure (Cont'd)
EC-278
DescriptionNCEC0349SYSTEM DESCRIPTIONNCEC0349S01
Sensor Input Signal to ECMECM
functionActuator
Crankshaft position sensor (POS) Engine speed
EGR control EGR volume control valve Mass air flow sensor Amount of intake air
Engine coolant temperature sensor Engine coolant temperature
Ignition switch Start signal
Throttle position sensor Throttle position
Vehicle speed sensor or ABS actuator and
electric unit (control unit)Vehicle speed
Battery Battery voltage
This system controls flow rate of EGR led from exhaust manifold
to intake manifold. The opening of the EGR by-pass passage in the
EGR volume control valve changes to control the flow rate. A
built-in step motor moves the valve in steps corresponding to the
ECM output pulses. The opening of the valve varies for optimum
engine control. The optimum value stored in the ECM is determined
by considering various engine conditions. The EGR volume control
valve remains close under the following conditions.
IExtremely light load engine operation
IMass air flow sensor malfunction
IEngine idling
ILow engine coolant temperature
IExcessively high engine coolant temperature
IHigh-speed engine operation
IWide open throttle
ILow battery voltage
IEngine starting
COMPONENT DESCRIPTIONNCEC0349S02EGR Volume Control ValveNCEC0349S0201The EGR volume control valve uses a step motor to control the flow
rate of EGR from exhaust manifold. This motor has four winding
phases. It operates according to the output pulse signal of the
ECM. Two windings are turned ON and OFF in sequence. Each
time an ON pulse is issued, the valve opens or closes, changing
the flow rate. When no change in the flow rate is needed, the ECM
does not issue the pulse signal. A certain voltage signal is issued
so that the valve remains at that particular opening.
SEF551W
SEF552W
DTC P1402 EGR FUNCTION (OPEN) (IF SO EQUIPPED)QG16I18DE
Description
EC-305