Page 665 of 2493
SEC500C
Component DescriptionNJEC1737The intake air temperature sensor is built into the mass air flow
sensor. The sensor detects intake air temperature and transmits a
signal to the ECM.
The temperature sensing unit uses a thermistor which is sensitive
to the change in temperature. Electrical resistance of the thermistor
decreases in response to the temperature rise.
Intake air temperature
ÉC (ÉF)Voltage*
VResistance
kW
25 (77) 3.3 1.9 - 2.1
80 (176) 1.28 0.31 - 0.37
*: These data are reference values and are measured between ECM terminal 64
(Intake air temperature sensor) and ground.
CAUTION:
Do not use ECM ground terminals when measuring input/
output voltage. Doing so may result in damage to the ECM's
transistor. Use a ground other than ECM terminals, such as
the ground.
INTAKE AIR TEMPERATURE SENSORQG
Component Description
EC-369
Page 666 of 2493
Wiring DiagramNJEC1738
YEC985
INTAKE AIR TEMPERATURE SENSORQG
Wiring Diagram
EC-370
Page 667 of 2493
Diagnostic ProcedureNJEC1739
1 CHECK OVERALL FUNCTION
1. Turn ignition switch ªONº.
2. Check voltage between ECM terminal 64 and ground with CONSULT-II or tester.
SEF004YA
OK or NG
OK©INSPECTION END
NG©GO TO 2.
2 CHECK POWER SUPPLY (Models with intake air temperature sensor in mass air flow sensor)
1. Turn ignition switch ªOFFº.
2. Disconnect mass air flow sensor harness connector.
JEF105Y
3. Turn ignition switch ªONº.
4. Check voltage between terminal 1 and ground with CONSULT-II or tester.
SEC503C
OK or NG
OK©GO TO 4.
NG©GO TO 3.
INTAKE AIR TEMPERATURE SENSORQG
Diagnostic Procedure
EC-371
Page 668 of 2493

3 DETECT MALFUNCTIONING PART
Check harness for open or short between ECM and intake air temperature sensor.
©Repair harness or connectors.
4 CHECK GROUND CIRCUIT
1. Turn ignition switch ªOFFº.
2. Check harness continuity between mass air flow sensor harness connector terminal 3 and engine ground.
Refer to wiring diagram.
Continuity should exist.
3. Also check harness for short to ground and short to power.
OK or NG
OK©GO TO 6.
NG©GO TO 5.
5 DETECT MALFUNCTIONING PART
Check harness for open or short between ECM and intake air temperature sensor.
©Repair open circuit or short to ground or short to power in harness or connectors.
6 CHECK INTAKE AIR TEMPERATURE SENSOR
Refer to ªComponent Inspectionº, EC-372.
OK or NG
OK©GO TO 7.
NG©Replace intake air temperature sensor.
7 CHECK INTERMITTENT INCIDENT
Perform ªTROUBLE DIAGNOSIS FOR INTERMITTENT INCIDENTº, EC-144.
©INSPECTION END
SEC516C
Component InspectionNJEC1740INTAKE AIR TEMPERATURE SENSORNJEC1740S01Check resistance between mass air flow sensor harness connec-
tor terminals 3 and 5.
Intake air temperature
ÉC (ÉF)Resistance kW
25 (77) 1.9 - 2.1
If NG, replace intake air temperature sensor.
INTAKE AIR TEMPERATURE SENSORQG
Diagnostic Procedure (Cont'd)
EC-372
Page 669 of 2493

SEF463R
SEF288D
Component DescriptionNJEC1214The heated oxygen sensor 1 (front) is placed into the exhaust
manifold. It detects the amount of oxygen in the exhaust gas com-
pared to the outside air. The heated oxygen sensor 1 (front) has a
closed-end tube made of ceramic zirconia. The zirconia generates
voltage from approximately 1V in richer conditions to 0V in leaner
conditions. The heated oxygen sensor 1 (front) signal is sent to the
ECM. The ECM adjusts the injection pulse duration to achieve the
ideal air-fuel ratio. The ideal air-fuel ratio occurs near the radical
change from 1V to 0V.
CONSULT-II Reference Value in Data Monitor
Mode
NJEC1215Specification data are reference values.
MONITOR ITEM CONDITION SPECIFICATION
HO2S1 (B1)
+Engine: After warming upMaintaining engine speed at 2,000
rpm0 - 0.3V¨Approx. 0.6 - 1.0V
HO2S1 MNTR
(B1)LEAN¨RICH
Changes more than 5 times during
10 seconds.
ECM Terminals and Reference ValueNJEC1216Specification 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)
62 WHeated oxygen sensor
1 (front)[Engine is running]
+After warming up to normal operating tempera-
ture and engine speed is 2,000 rpm0 - Approximately 1.0V
SEF008W
HEATED OXYGEN SENSOR 1 (FRONT)QG
Component Description
EC-373
Page 670 of 2493
Wiring DiagramNJEC1220
YEC986
HEATED OXYGEN SENSOR 1 (FRONT)QG
Wiring Diagram
EC-374
Page 671 of 2493

Diagnostic ProcedureNJEC1221
1 INSPECTION START
Do you have CONSULT-II?
YesorNo
Ye s©GO TO 2.
No©GO TO 3.
2 CHECK OVERALL FUNCTION
With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select ªHO2S1 MNTR (B1)º in ªDATA MONITORº mode with CONSULT-II.
3. Keep the engine speed at 2,000 rpm under no load, and make sure that the monitors fluctuate between LEAN and
RICH more than five times in 10 seconds.
SEF218Z
OK or NG
OK©INSPECTION END
NG©GO TO 4.
3 CHECK OVERALL FUNCTION
Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Set voltmeter probes between ECM terminal 62 (HO2S1 signal) and engine ground.
3. Check the following with engine speed held at 2,000 rpm constant under no load.
SEC518C
CAUTION:
Discard any heated oxygen sensor which has been dropped from a height of more than 0.5 m (19.7 in) onto a
hard surface such as a concrete floor; use a new one.
OK or NG
OK©INSPECTION END
NG©GO TO 4.
HEATED OXYGEN SENSOR 1 (FRONT)QG
Diagnostic Procedure
EC-375
Page 672 of 2493
4 RETIGHTEN GROUND SCREWS
1. Turn ignition switch ªOFFº.
2. Loosen and retighten engine ground screws.
JEF104Y
3. Disconnect heated oxygen sensor 1 (front) harness connector.
SEF012XA
©GO TO 5.
5 RETIGHTEN HEATED OXYGEN SENSOR 1 (FRONT)
Loosen and retighten corresponding heated oxygen sensor 1 (front).
Tightening torque:
40 - 50 N´m (4.1 - 5.1 kg-m, 30 - 37 ft-lb)
©GO TO 6.
6 CHECK INPUT SIGNAL CIRCUIT
1. Disconnect ECM harness connector.
2. Check harness continuity between ECM terminal 62 and heated oxygen sensor 1 (front) harness connector terminal 2.
Refer to wiring diagram.
Continuity should exist.
3. Check harness continuity between ECM terminal 62 (or terminal 2) and ground.
Continuity should not exist.
4. Also check harness for short to power.
OK or NG
OK©GO TO 7.
NG©Repair open circuit or short to ground or short to power in harness or connectors.
HEATED OXYGEN SENSOR 1 (FRONT)QG
Diagnostic Procedure (Cont'd)
EC-376