heater control SUZUKI SWIFT 2004 2.G Service User Guide

Downloaded from www.Manualslib.com manuals search engine 1A-28 Engine General Information and Diagnosis:
) *P0031 HO2S heater control circuit low
(Sensor-1) Heater voltage is less than specification while heater ON. 2 driving
cycles
) *P0032 HO2S heater control circuit
high (Sensor-1) Heater voltage is more than
specification while heater
ON. 2 driving
cycles
) *P0037 HO2S heater control circuit low
(Sensor-2) Heater voltage is less than specification while heater ON. 2 driving
cycles
) *P0038 HO2S heater control circuit
high (Sensor-2) Heater voltage is more than
specification while heater
ON. 2 driving
cycles
)
U *P0101 Mass or volume air flow circuit
range/performance MAF sensor volume is more
than specification or less
than specification. 2 driving
cycles
) *P0102 Mass or volume air flow circuit
low input Output voltage of MAF sensor is less than specification. 1 driving
cycle
) *P0103 Mass or volume air flow circuit
high input Output voltage of MAF sensor is more than specification. 1 driving
cycle
)
U *P0106 Manifold absolute pressure/
barometric pressure circuit
range/performance Difference between Max. manifold absolute pressure
value and Min. manifold pressure value is less than
specification or difference between barometric pressure
value and manifold pressure value is less than
specification
2 driving
cycles
) *P0107 Manifold absolute pressure/
barometric pressure circuit low
input Output voltage of MAP sensor
is less than specification.1 driving
cycle
) *P0108 Manifold absolute pressure/
barometric pressure circuit high
input Output voltage of MAP sensor is more than specification.
1 driving
cycle
)
U *P0111 Intake air temperature sensor 1
circuit range/performance Variation of intake air temperature from engine start is
less than specification. 2 driving
cycles
) *P0112 Intake air temperature sensor 1
circuit low Circuit voltage of IAT sensor is less than specification. 1 driving
cycle
) *P0113 Intake air temperature sensor 1
circuit hig

h Circuit voltage of IAT sensor
is more than specification. 1 driving
cycle
)
U *P0116 Engine coolant temperature
circuit range/performance Engine coolant temperature is less than specified
temperature for specified time from engine start. 2 driving
cycles
) *P0117 Engine coolant temperature
circuit low Circuit voltage of ECT sensor
is less than specification. 1 driving
cycle
) *P0118 Engine coolant temperature
circuit high Circuit voltage of ECT sensor
is more than specification. 1 driving
cycle
) *P0122 Throttle/pedal position sensor/
switch “A” circuit low Output voltage of TP sensor (main) is lower than
specification. 1 driving
cycle
) *P0123 Throttle/pedal position sensor/
switch “A” circuit high Output voltage of TP sensor (main) is higher than
specification. 1 driving
cycle
)
U *P0131 O2 sensor (HO2S) circuit low
voltage (Sensor-1)
Max. output voltage of HO2S-1
is less than specification.2 driving
cycles
)
U *P0132 O2 sensor (HO2S) circuit high
voltage (Sensor-1)
Min. output voltage of HO2S-1
is more than specification. 2 driving
cycles
)
U *P0133 O2 sensor (HO2S) circuit slow
response (Sensor-1) Response time of HO2S-1 output voltage between rich
and lean is longer than specification. 2 driving
cycles
) *P0134 O2 sensor (HO2S) circuit no
activity detected (Sensor-1) Output voltage of HO2S-1 is
more than specification or
less than specification. (or HO2S-1 circuit open or short) 2 driving
cycles
)
U *P0137 O2 sensor (HO2S) circuit low
voltage (Sensor-2) Output voltage of HO2S-2 is
less than specification while
engine is idling after driving with high engine load and
Max. output voltage of HO2S-2 minus Min. output voltage
of HO2S-2 is less than specification. 2 driving
cycles
)
U *P013

8 O2 sensor (HO2S) circuit high
voltage (Sensor-2) Output voltage of HO2S-2 is
more than specification while
engine is idling after driving with high engine load and
Max. output voltage of HO2S-2 minus Min. output voltage
of HO2S-2 is less than specification. 2 driving
cycles
DTC No. Detecting item
Detecting condition
(DTC will set when detecting:) MIL

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-31
Fail-Safe TableS7RS0B1104006
When any of the following DTCs is detected, ECM enters fail-safe mode as long as malfunction continues to exist but
that mode is canceled when ECM de tects normal condition after that.
)
*P2123 Throttle/pedal position sensor/
switch “D” (main) circuit high
input Output voltage of APP sensor (main) is higher than
specification.
1 driving
cycle
) *P2127 Throttle/pedal position sensor/
switch “E” (sub) circuit low
input Output voltage of APP sens
or (sub) is lower than
specification. 1 driving
cycle
) *P2128 Throttle/pedal position sensor/
switch “E” (sub) circuit high
input Output voltage of APP sensor (sub) is higher than
specification.
1 driving
cycle
) *P2135 Throttle/pedal position sensor/
switch “A”/“B” (main / sub)
voltage correlation Difference between the opening angle based on TP
sensor (main) and the opening angle based on TP sensor
(sub) is more than specification.
1 driving
cycle
) *P2138 Throttle/pedal position sensor/
switch “D”/“E” (main / sub)
voltage correlation Difference between the opening angle based on APP
sensor (main) and the opening angle based on APP
sensor (sub) is more
than specification. 1 driving
cycle
)
U *P2227 Barometric pressure circuit
range/performance Difference of barometric pressure value and intake
manifold pressure value is
more than specification at
engine start. 2 driving
cycles
) *P2228 Barometric pressure circuit low Barometric pressure sens
or voltage is less than
specification. 1 driving
cycle
) *P2229 Barometric pressure circuit
high Barometric pressure sensor voltage is more than
specification. 1 driving
cycle
) P1614 Transponder response error
Refer to “Diagnostic Trouble Code (DTC) Table in Section
10C”. —

) P1615 ID code does not registered
(vehicle equipped with keyless
start system only)
) P1616 Different registration ID codes
(vehicle equipped with keyless
start system only)
) P1618 CAN communication error
(reception error for keyless
start control module) (vehicle
equipped with keyless start
system only)
) P1621 Immobilizer communication
line error
) P1622
EEPROM error
) P1623 Unregistered transponder
) P1625 Immobilizer antenna error
) P1636 Immobilizer information
registration failure
) P1638 Immobilizer information
mismatched
DTC No. Detecting item
Detecting condition
(DTC will set when detecting:) MIL
DTC No.
Detected item Fail-safe operation
) P0031 HO2S heater control circuit low (Sensor-1)
ECM stops air/fuel ratio control.
) P0032 HO2S heater control circuit high (Sensor-1)
) P0102 Mass or volume air flow circuit low input • ECM controls injector drive time (fuel injection
volume) according to throttle valve opening
(closed throttle position or not).
• ECM stops EGR control.
)
P0103 Mass or volume air flow circuit high input
) P0112 Intake air temperature sensor 1 circuit low ECM controls actuators assuming that intake air
temperature is 20 °C (68 ° F).
) P0113 Intake air temperature sensor 1 circuit high

Downloaded from www.Manualslib.com manuals search engine 1A-54 Engine General Information and Diagnosis:
DTC P0031 / P0032: HO2S Heater Control Circuit Low / High (Sensor-1)S7RS0B1104015
Wiring Diagram
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature.
4) Run engine at idle speed for 1 min. or more.
5) Check DTC and pending DTC.
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and confirm that the trouble has been corrected.

E23 C37
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
BLK/WHT
WHT
11
GRN
3 9
E23-29
WHT
YEL
BLK/WHT
BLKC37-46
C37-10
C37-57
6
7
10
BLK
BLUWHT
BLK/RED
4
5
8
12
1
I6RS0C110006-03
1. Main fuse box
4. Junction block assembly 7. Heater 10. To HO2S-2
2. Shield wire 5. “IG COIL” fuse8. To HO2S-2 heater 11. Individual circuit fuse box No.1
3. Ignition switch 6. HO2S-19. ECM 12. “IG ACC” fuse
DTC detecting condition Trouble area
HO2S-1 heater voltage is more than specified value or lower
than specified value for 5 seconds continuously.
(2 driving cycle detection logic) • HO2S-1 heater circuit
• HO2S-1 heater
•ECM

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-55
StepAction YesNo
1 Was “Engine and Emission Control System Check”
performed? Go to Step 2.
Go to “Engine and
Emission Control
System Check”.
2 HO2S-1 heater power circuit check
1) Disconnect connector from HO 2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 at “BLK/WHT” and “BLK/RED” wire terminals.
3) If wire and connection are OK, measure voltage between “BLK/WHT” wire terminal and engine ground
with ignition switch turned ON.
Is voltage over 10 V? Go to Step 3.
“BLK/WHT” wire is open
circuit or shorted to
ground circuit.
3 HO2S-1 heater power circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “BLK/WHT” wire terminal of HO2S-1 connector and “E 23-29” terminal of ECM
connector.
Is resistance below 5
Ω? Go to Step 4. “BLK/WHT” wire is high
resistance circuit.
4 HO2S-1 heater drive circuit check
1) Measure resistance between “C37-46” terminal of ECM
connector and vehicle body ground.
Is resistance infinity? Go to Step 5. “BLK/RED” wire is
shorted to ground
circuit.
5 HO2S-1 heater drive circuit check
1) Turn ON ignition switch.
2) Measure voltage between “C37-46” terminal of ECM
connector and vehicle body ground.
Is voltage 0 V? Go to Step 6. “BLK/RED” wire is
shorted to power circuit.
6 HO2S-1 heater drive circuit check
1) Connect connector to HO2S-1 with ignition switch turned
OFF.
2) Turn ON ignition switch.
3) Measure voltage between “C37-46” terminal of ECM connector and vehicle body ground with connector
disconnected from ECM.
Is voltage over 10 V? Go to Step 7. “BLK/RED” wire is open
circuit.
7 HO2S-1 heater check
1) Disconnect HO2S-1 connector with ignition switch
turned OFF.
2) Check HO2S-1 heater resistance referring to “HO2S-1 and HO2S-2 Heater On-Vehicle Inspection in Section
1C”.
Is resistance within specified value range? Go to Step 8. Replace HO2S-1.
8 HO2S-1 heater power circuit check
1) Connect connector to HO2S-1 with ignition switch turned
OFF.
2) Measure resistance between “E23-29” and “C37-46” terminals of ECM connector.
It resistance below 12
Ω? Substitute a known-
good ECM and recheck.
“BLK/WHT”, “BLK/RED”
and / or “BLK” wire is
high resistance circuit.

Downloaded from www.Manualslib.com manuals search engine 1A-56 Engine General Information and Diagnosis:
DTC P0037 / P0038: HO2S Heater Control Circuit Low / High (Sensor-2)S7RS0B1104016
Wiring Diagram
DTC Detecting Condition and Trouble Area
DTC Confirmation Procedure1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature.
4) Run engine at idle speed for 1 min.
5) Check DTC and pending DTC.
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and confirm that the trouble has been corrected.

E23 C37
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
34
1819
567
1011
17
20
47 46
495051
2122
52 16
25 9
24
14
29
55
57 54 53
59
60 58 2
262728
15
30
56 4832 31
34353637
40
42 39 38
44
45 43 41 331
1213
238
BLK/WHT
WHT
11
GRN
3 9
E23-29
BRN
YEL
BLK/WHT
BLKC37-47
C37-11
C37-57
6
2
7
10
BLK
BLUWHT
RED/BLU
1
4
5
8
12
5V
I6RS0C110007-01
1. Main fuse box 4. Junction block assembly 7. Heater 10. To HO2S-1
2. Shield wire 5. “IG COIL” fuse8. To HO2S-1 heater 11. Individual circuit fuse box No.1
3. Ignition switch 6. HO2S-29. ECM 12. “IG ACC” fuse
DTC detecting condition Trouble area
HO2S-2 heater voltage is more than specified value or less than
specified value for 5 seconds continuously
(2 driving cycle detection logic) • HO2S-2 heater
• HO2S-2 heater circuit
•ECM

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-57
StepAction YesNo
1 Was “Engine and Emission Control System Check”
performed? Go to Step 2.
Go to “Engine and
Emission Control
System Check”.
2 HO2S-2 heater power circuit check
1) Disconnect connector from HO 2S-2 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-2 at “BLK/WHT” and “RED/BLU” wire terminals.
3) If wire and connection are OK, measure voltage between “BLK/WHT” wire terminal of HO2S-2 connector
and engine ground with ignition switch turned ON.
Is voltage over 10 V? Go to Step 3.
“BLK/WHT” wire is open
circuit or shorted to
ground circuit.
3 HO2S-2 heater power circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “BLK/WHT” wire terminal of HO2S-2 connector and “E23-29” terminal wire of ECM
connector.
Is resistance below 5
Ω? Go to Step 4. “BLK/WHT” wire is high
resistance circuit.
4 HO2S-2 heater drive circuit check
1) Measure resistance between “RED/BLU” wire terminal of
HO2S-2 connector and vehicle body ground.
Is resistance infinity? Go to Step 5. “RED/BLU” wire is
shorted to ground
circuit.
5 HO2S-2 heater drive circuit check
1) Turn ON ignition switch.
2) Measure voltage between “RED/BLU” wire terminal of
HO2S-2 connector and vehicle body ground.
Is voltage 0 V? Go to Step 6. “RED/BLU” wire is
shorted to power circuit.
6 HO2S-2 heater drive circuit check
1) Connect connector to HO2S-2 with ignition switch turned
OFF.
2) Turn ON ignition switch.
3) Measure voltage between “C37-47” terminal of disconnected ECM connector and vehicle body ground.
Is voltage over 10 V? Go to Step 7.
“RED/BLU” wire is open
circuit.
7 HO2S-2 heater check
1) Disconnect HO2S-2 connector with ignition switch
turned OFF.
2) Check HO2S-2 heater resistance referring to “HO2S-1 and HO2S-2 Heater On-Vehicle Inspection in Section
1C”.
Is resistance within specified value? Go to Step 8.
Replace HO2S-2.
8 HO2S-2 heater power circuit check
1) Connect connector to HO2S-2 with ignition switch turned
OFF.
2) Measure resistance between “E23-29” and “C37-47” terminals of ECM connector.
Is resistance below 30
Ω? Substitute a known-
good ECM and recheck.
“RED/BLU” wire is high
resistance circuit.

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-77
DTC Confirmation Procedure
WARNING!
• When performing a road test, select a place where there is no traffic or possibility of a traffic accident and be very careful during testing to avoid occurrence of an accident.
• Road test should be carried out by 2 persons, a driver and tester, on a level road.

NOTE
Check to make sure that following conditions ar e satisfied when using this “DTC Confirmation
Procedure”.
• Intake air temperature at engine start: –10 °C (14 ° F) to 80 °C (176 °F)
• Intake air temperature: –10 °C (14 °F) to 70 °C (158 °F)
• Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)

1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch, clear DTC.
3) Start engine.
4) Drive vehicle at 40 mph (60 km/h) or higher for 20 min. or more.
5) Stop vehicle.
6) Check DTC and pending DTC.
DTC Troubleshooting
NOTE
• When measuring circuit voltage, resistance and/ or pulse signal at ECM connector, connect the
special tool to ECM and/or the ECM connectors re ferring to “Inspection of ECM and Its Circuits”.
• Upon completion of inspection and repair work, perform “DTC Confirmation Procedure” and confirm that the trouble has been corrected.

Step Action YesNo
1 Was “Engine and Emission Control System Check”
performed? Go to Step 2.
Go to “Engine and
Emission Control
System Check”.
2 DTC check
1) With ignition switch turned OFF, install scan tool to DLC.
2) Turn ON ignition switch and check DTC with scan tool.
Is DTC P0118 displayed? Go to “DTC P0118:
Engine Coolant
Temperature Circuit
High”.
Go to Step 3.
3 Engine coolant temp. check
1) Turn ON ignition switch and check engine coolant temp.
displayed on scan tool.
2) Warm up engine to normal operating temp. and check engine coolant temp. displayed on scan tool.
Does engine coolant te mp. vary more than 1
°C (1 °F) and
rise higher than 70
°C (158 °F)? Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection
Inspection in Section
00”.
Go to Step 4.
4 Thermostat check
Is there a symptom due to thermostat remaining open (it
takes a long time before vehicle heater becomes effective or
before engine is warmed to normal operating temp., etc.)? Check thermostat
referring to “Thermostat
Inspection in Section
1F”.
Go to Step 5.

Downloaded from www.Manualslib.com manuals search engine 1A-90 Engine General Information and Diagnosis:
4HO2S-1 ground check
1) Disconnect connector from HO 2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 connector at “BLK/RED”, “WHT”, “BLK /WHT” and “YEL” wire
terminals.
3) If connections are OK, m easure resistance between
“YEL” wire terminal of HO2S-1 connector and engine
ground.
Is measured resistance less than 5
Ω? Go to Step 5. “YEL” wire is open or
high resistance circuit.
Poor “C37-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
5 Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its br acket with ECM connectors
connected.
3) Measure resistance between “WHT” wire terminal of HO2S-1 connector and “C37-10” terminal of ECM
connector.
Is resistance less than 5
Ω? Go to Step 6. “WHT” wire is high
resistance circuit or
open circuit. Poor “C37-
10” terminal connection.
Faulty ECM ground. If
they are OK, substitute
a known-good ECM and
recheck.
6 Wire circuit check
1) Disconnect connectors from ECM with ignition switch
turn OFF.
2) Measure resistance between “WHT” wire terminal of HO2S-1 connector and vehicle body ground.
Is resistance infinity? Go to Step 7. “WHT” wire is shorted to
ground circuit.
7 HO2S-1 signal circuit check
1) Measure voltage between “WHT” wire terminal of HO2S-
1 connector and vehicle body ground.
Is voltage 0 V? Go to Step 8. “WHT” wire is shorted to
other circuit.
8 HO2S-1 heater circuit check
1) Check HO2S-1 heater circuit referring to “DTC P0031 /
P0032: HO2S Heater Control Circuit Low / High
(Sensor-1)”.
Is circuit in good condition? Go to Step 9. Repair HO2S-1 circuit.
9 Exhaust system check
1) Check exhaust system for exhaust gas leakage.
Is it OK? Go to Step 4 in “DTC
P0171 / P0172: Fuel
System Too Lean /
Rich”.
If it is in good condition,
go to Step 10.Repair leakage of
exhaust system.
10 Air intake system check
1) Check air intake system for clog or leak.
Is it OK? Check HO2S-1 referring
to “HO2S-1 and HO2S-
2 Heater On-Vehicle
Inspection in Section
1C”.
If it is in good condition,
substitute a known-
good ECM and recheck.Repair or replace air
intake system.
Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-93
2HO2S-1 output voltage check
1) Connect scan tool to DLC with ignition switch turned
OFF.
2) Warm up engine to normal operating temperature and keep it at 2000 r/min. for 60 sec.
3) Repeat racing engine (Repeat depressing accelerator pedal 5 to 6 times continuous ly to enrich A/F mixture and
take foot off from pedal to enlean it) and check HO2S
output voltages displayed on scan tool.
Is over 0.6 V and below 0.3 V indicated? Intermittent trouble.
Check for intermittent
referring to “Intermittent
and Poor Connection
Inspection in Section
00”. If check result is
OK, go to Step 3.
Go to Step 3.
3 HO2S-1 ground check
1) Disconnect connector from HO 2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 at “BLK/RED”, “WHT”, “BLK/WHT” and “YEL” wire terminals.
3) If wire and connection are OK, measure resistance between “YEL” wire terminal of HO2S-1 connector and
engine ground.
Is resistance less than 5
Ω? Go to Step 4. “YEL” wire is open or
high resistance circuit.
Poor “C37-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
4 Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its br acket with ECM connectors
connected.
3) Measure resistance between “WHT” wire terminal of HO2S-1 connector and “C37-10” terminal of ECM
connector.
Is resistance less than 5
Ω? Go to Step 5. “WHT” wire is high
resistance circuit or
open circuit. Poor “C37-
10” terminal connection
of ECM connector.
Faulty ECM ground. If
they are OK, substitute
a known-good ECM and
recheck.
5 Wire circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “WHT” wire terminal of HO2S-1 connector and vehicle body ground.
Is resistance infinity? Go to Step 6. “WHT” wire is shorted to
ground circuit.
6 HO2S-1 heater circuit check
1) Check HO2S-1 heater circuit referring to “DTC P0031 /
P0032: HO2S Heater Control Circuit Low / High
(Sensor-1)”.
Is it in good condition? Go to Step 7. Repair HO2S-1 circuit.
7 Exhaust system check
1) Check exhaust system for exhaust gas leakage.
Is it OK? Go to Step 4 in “DTC
P0171 / P0172: Fuel
System Too Lean /
Rich”.
If it is in good condition,
go to Step 8.Repair leakage of
exhaust system.
8 Air intake system check
1) Check air intake system for clog or leak.
Is it OK? Check HO2S-1 referring
to “HO2S-1 and HO2S-
2 Heater On-Vehicle
Inspection in Section
1C”.
If it is in good condition,
substitute a known-
good ECM and recheck.Repair or replace air
intake system.
Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine 1A-96 Engine General Information and Diagnosis:
4HO2S-2 ground check
1) Disconnect connector from HO 2S-2 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-2 connector at “RED/BLU”, “BRN”, “YEL” and “BLK/WHT” wire
terminals.
3) If connections are OK, m easure resistance between
“YEL” wire terminal of HO2S-2 connector and engine
ground.
Is resistance less than 5
Ω? Go to Step 5. “YEL” wire is open or
high resistance circuit.
Poor “C37-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
5 Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its br acket with ECM connectors
connected.
3) Measure resistance between “BRN” wire terminal of HO2S-2 connector and “C37-11” terminal of ECM
connector.
Is resistance less than 5
Ω? Go to Step 6. “BRN” wire is high
resistance circuit or
open circuit. Poor “C37-
11” terminal connection.
If they are OK,
substitute a known-
good ECM and recheck.
6 Wire circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “BRN” wire terminal of HO2S-2 connector and vehicle body ground.
Is resistance infinity? Go to Step 7. “BRN” wire is shorted to
ground circuit.
7 HO2S-2 signal circuit check
1) Measure voltage between “BRN” wire terminal of HO2S-
2 connector and vehicle body ground.
Is voltage 0 V? Go to Step 8. “BRN” wire is shorted to
other circuit.
8 HO2S-2 heater circuit check
1) Check HO2S-2 heater circuit referring to “DTC P0037 /
P0038: HO2S Heater Control Circuit Low / High
(Sensor-2)”.
Is circuit in good condition? Go to Step 9. Repair HO2S-2 circuit.
9 Exhaust system check
1) Check exhaust system for exhaust gas leakage.
Is it OK? Go to Step 4 in “DTC
P0171 / P0172: Fuel
System Too Lean /
Rich”.
If it is in good condition,
go to Step 10.Repair leakage of
exhaust system.
10 Air intake system check
1) Check air intake system for clog or leak.
Is it OK? Check HO2S-2 referring
to “HO2S-1 and HO2S-
2 Heater On-Vehicle
Inspection in Section
1C”.
If it is in good condition,
substitute a known-
good ECM and recheck.Repair or replace air
intake system.
Step Action Yes No