
On Board Diagnosis LogicNEEC0192With 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. 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 1Density 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
0172+Fuel injection system does not operate properly.
+The amount of mixture ratio compensation is too large.
(The mixture ratio is too rich.)+Heated oxygen sensor 1
+Injectors
+Exhaust gas leaks
+Incorrect fuel pressure
+Mass air flow sensor
SEF215Z
SEF058Y
DTC Confirmation ProcedureNEEC0193NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch OFF and wait at least 5 seconds before
conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch OFF and wait at least 5 seconds.
3) Turn ignition switch ON 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 P0172 should be detected at this stage, if a
malfunction exists. If so, go to ªDiagnostic Procedureº,
EC-3247.
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-3247. If engine does
not start, remove ignition plugs and check for fouling, etc.
AEC131A
With GST
1) Start engine and warm it up to normal operating temperature.
2) Turn ignition switch OFF and wait at least 5 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 P0102 is
detected.
6) Select ªMODE 4º with GST and erase the 1st trip DTC P0102.
DTC P0172 FUEL INJECTION SYSTEM
FUNCTION
KA24DE (EURO OBD)
On Board Diagnosis Logic
EC-3244

On Board Diagnosis LogicNEEC0202When a misfire occurs, 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 (OBD) 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.
2. Two Trip Detection Logic (Exhaust quality deterioration)
For misfire conditions that will not damage the TWC (but will affect vehicle 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
0300+Multiple cylinders misfire.+Improper spark plug
+Insufficient compression
+Incorrect fuel pressure
+The injector circuit is open or shorted
+Injectors
+Intake air leak
+The ignition secondary circuit is open or shorted
+Lack of fuel
+Drive plate/Flywheel
+Heated oxygen sensor 1
+Incorrect distributor rotor P0301
0301+No. 1 cylinder misfires.
P0302
0302+No. 2 cylinder misfires.
P0303
0303+No. 3 cylinder misfires.
P0304
0304+No. 4 cylinder misfires.
SEF174Y
DTC Confirmation ProcedureNEEC0203CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch OFF and wait at least 5 seconds before
conducting the next test.
With CONSULT-II
1) Turn ignition switch ON, and select ªDATA MONITORº mode
with CONSULT-II.
2) Start engine and warm it up to normal operating temperature.
DTC P0300 - P0304 NO.4-1CYLINDER MISFIRE, MULTIPLE CYLINDER
MISFIRE
KA24DE (EURO OBD)
On Board Diagnosis Logic
EC-3251

SEF598K
Component DescriptionNEEC0206The 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.
ECM Terminals and Reference ValueNEEC0207Specification 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)
64 W Knock sensor[Engine is running]
+Idle speedApproximately 2.4V
On Board Diagnosis LogicNEEC0208
DTC No.Trouble diagnosis
nameDTC Detecting Condition Possible Cause
P0327
0327Knock sensor circuit
low inputAn excessively low voltage from the sensor is sent
to ECM.+Harness or connectors
(The sensor circuit is open or
shorted.)
+Knock sensor P0328
0328Knock sensor circuit
high inputAn excessively high voltage from the sensor is
sent to ECM.
SEF058Y
DTC Confirmation ProcedureNEEC0209NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch OFF and wait at least 5 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 ON 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-3262.
With GST
Follow the procedure ªWith CONSULT-IIº.
DTC P0327, P0328 KSKA24DE (EURO OBD)
Component Description
EC-3260

SEF928V
SEF853B
Component DescriptionNEEC0220The camshaft position sensor is a basic component of the engine
control system. It monitors engine speed and piston position.
These input signals to the engine control system are used to con-
trol fuel injection, ignition timing and other functions.
The camshaft position sensor has a rotor plate and a wave-form-
ing circuit. The rotor plate has 360 slits for a 1É (POS) signal and
4 slits for a 180É (REF) signal. The wave-forming circuit consists
of Light Emitting Diodes (LED) and photo diodes.
The rotor plate is positioned between the LED and the photo diode.
The LED transmits light to the photo diode. As the rotor plate turns,
the slits cut the light to generate rough-shaped pulses. These
pulses are converted into on-off signals by the wave-forming circuit
and sent to the ECM.
The distributor is not repairable and must be replaced as an
assembly except distributor cap and rotor head.
ECM Terminals and Reference ValueNEEC0221Specification 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)
4 L/BECM relay (Self shut-
off)[Engine is running]
[Ignition switch OFF]
+For a few seconds after turning ignition switch
OFF0-1V
[Ignition switch OFF]
+More than a few seconds after turning ignition
switch OFFBATTERY VOLTAGE
(11 - 14V)
44*1
48*1
(49)*2
(53)*2OR
OR
OR
ORCamshaft position sen-
sor (Reference signal)[Engine is running](Warm-up condition)
+Idle speed0.2 - 0.5V
[Engine is running]
+Engine speed is 2,000 rpm0 - 0.5V
DTC P0340 CMP SENSORKA24DE (EURO OBD)
Component Description
EC-3270

SEF197Y
SEF198Y
DTC Confirmation Procedure=NEEC0290CAUTION:
Always drive vehicle at a safe speed.
NOTE:
If ªDTC Confirmation Procedureº has been previously conducted,
always turn ignition switch OFF and wait at least 5 seconds before
conducting the next test.
With CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Select ªCLSD THL/P SWº in ªDATA MONITORº mode with
CONSULT-II and check the value under the following condi-
tions.
Condition Signal indication
Throttle valve: Idle position ON
Throttle valve: Slightly open OFF
If the result is NG, go to ªDiagnostic Procedureº, EC-3304.
If OK, go to following step.
3) Select ªDATA MONITORº mode with CONSULT-II.
4) Drive the vehicle for at least 5 consecutive seconds under the
following condition.
THRTL POS SEN More than 2.5V
VHCL SPEED SE More than 4 km/h (2 MPH)
Selector lever Suitable position
Driving pattern Driving vehicle uphill (Increased engine load)
will help maintain the driving conditions
required for this test.
5) If 1st trip DTC is detected, go to ªDiagnostic Procedureº,
EC-3304.
SEF422Q
Overall Function CheckNEEC0291Use this procedure to check the overall function of the closed
throttle position switch circuit. During this check, a 1st trip DTC
might not be confirmed.
Without CONSULT-II
1) Start engine and warm it up to normal operating temperature.
2) Check the voltage between ECM terminal 28 (Closed throttle
position switch signal) and ground under the following condi-
tions.
Condition Voltage
At idle Battery voltage
At 2,000 rpm Approximately0-1V
3) If NG, go to ªDiagnostic Procedureº, EC-3304.
DTC P0510 CTP SWITCHKA24DE (EURO OBD)
DTC Confirmation Procedure
EC-3302

Fuel Pressure RegulatorNEEC0467
Fuel pressure at idling
kPa (bar, kg/cm2, psi)Vacuum hose is connected Approximately 235 (2.35, 2.4, 34)
Vacuum hose is disconnected Approximately 294 (2.94, 3.0, 43)
Idle Speed and Ignition TimingNEEC0468
Base idle speed*1 rpm No-load*3 (in ªNº position) 650±50
Target idle speed*2 rpm No-load*3 (in ªNº position) 700±50
Air conditioner: ON rpm In ªNº position 850 or more
Ignition timing*1 In ªNº position 15ɱ2É BTDC
*1: Throttle position sensor harness connector disconnected or using CONSULT-II ªWORK SUPPORTº mode
*2: Throttle position sensor harness connector connected
*3: Under the following conditions:
+Air conditioner switch: OFF
+Electrical load: OFF (Lights, heater fan & rear window defogger)
+Steering wheel: Kept in straight-ahead position
Ignition CoilNEEC0469
Primary voltage VBattery voltage 12
Primary resistance [at 20ÉC (68ÉF)]WApproximately 1.0
Secondary resistance [at 20ÉC (68ÉF)] kWApproximately 10
Mass Air Flow SensorNEEC0470
Supply voltage VBattery voltage (11 - 14)
Output voltage V0.9 - 1.8*
Mass air flow
(Using CONSULT-II or GST) g´m/sec0.9 - 5.8 at idle*
7.5 - 13.2 at 2,500 rpm*
*: Engine is warmed up to normal operating temperature and idling under no-load.
Engine Coolant Temperature SensorNEEC0471
Temperature ÉC (ÉF) Resistance kW
20 (68) 2.1 - 2.9
50 (122) 0.68 - 1.00
90 (194) 0.236 - 0.260
Fuel PumpNEEC0473
Resistance [at 25ÉC (77ÉF)]W0.2 - 5.0
IACV-AAC ValveNEEC0474
Resistance [at 25ÉC (77ÉF)]WApproximately 10.0
InjectorNEEC0475
Resistance [at 25ÉC (77ÉF)]W7.3 - 9.9
SERVICE DATA AND SPECIFICATIONS
(SDS)
KA24DE (EURO OBD)
Fuel Pressure Regulator
EC-3398

Precautions
+Always use a 12 volt battery as power source.
+Do not attempt to disconnect battery cable while engine
is running.
+Before connecting or disconnecting the ECM harness
connector, turn ignition switch OFF and disconnect
negative battery terminal. Failure to do so may damage
the ECM because battery voltage is applied to ECM even
if ignition switch is turned off.
+Before removing parts, turn off ignition switch and then
disconnect battery ground cable.
+Do not disassemble ECM.
+If a battery terminal is disconnected, the memory will
return to the ECM value.
The ECM will now start to self-control at its initial value.
Engine operation can vary slightly when the terminal is
disconnected. However, this is not an indication of a
problem. Do not replace parts because of a slight varia-
tion.
+When ECM is removed for inspection, make sure to
ground the ECM mainframe.
+When connecting engine control system harness
connector, tighten securing bolt until the gap between
the orange indicators disappears.
: 3.0 - 5.0 Nzm (0.3 - 0.5 kg-m, 26 - 43 in-lb)
+When connecting or disconnecting pin connectors into
or from ECM, take care not to damage pin terminals
(bend or break).
Make sure that there are not any bends or breaks on
ECM pin terminal, when connecting pin connectors.
+Securely connect ECM harness connectors.
A poor connection can cause an extremely high (surge)
voltage to develop in the circuit, thus resulting in dam-
age to ICs.
+Keep ECM harness at least 10 cm (3.9 in) away from
adjacent harnesses, to prevent an ECM system malfunc-
SEF706Y
SEC220B
SEF665S
SEF308Q
SEF291H
PRECAUTIONSYD25DDTi
EC-3402

DTC and MIL Detection Logic
When a malfunction is detected, the malfunction (DTC) is stored in the ECM memory.
The MIL will light up each time the ECM detects malfunction. For diagnostic items causing the MIL to light
up, refer to ªTROUBLE DIAGNOSIS Ð INDEXº, EC-3400.
Diagnostic Trouble Code (DTC)
HOW TO READ DTC
The DTC can be read by the following methods.
Without CONSULT-II
ECM displays the DTC by a set of four digit numbers with MIL illumination in the diagnostic test mode II
(Self-diagnostic results). Example: 0407, 1004, etc.
With CONSULT-II
CONSULT-II displays the DTC in ªSELF-DIAG RESULTSº mode. Examples: ªCRANK POS SEN (TDC)º, etc.
HOW TO ERASE DTC
How to erase DTC (
With CONSULT-II)
1.If the ignition switch stays ªONº after repair work, be sure to turn ignition switch ªOFFº once. Wait at least
5 seconds and then turn it ªONº (engine stopped) again.
2. Touch ªENGINEº.
3. Touch ªSELF-DIAG RESULTSº.
4. Touch ªERASEº. (The DTC in the ECM will be erased.)
The emission related diagnostic information in the ECM can be erased by selecting ªERASEº in the ªSELF-
DIAG RESULTSº mode with CONSULT-II.
How to erase DTC (Without CONSULT-II)
1. If the ignition switch stays ªONº after repair work, be sure to turn ignition switch ªOFFº once. Wait at least
5 seconds and then turn it ªONº (engine stopped) again.
2. Change the diagnostic test mode from Mode II to Mode I by using the data link connector. (See
EC-3432.)
The emission related diagnostic information in the ECM can be erased by changing the diagnostic test mode.
+If the battery is disconnected, the emission-related diagnostic information will be lost after
approx. 24 hours.
SEC944C
ON BOARD DIAGNOSTIC SYSTEM DESCRIPTIONYD25DDTi
EC-3428