
EC-230
< SERVICE INFORMATION >
DTC P0133 A/F SENSOR 1
3.CHECK EXHAUST GAS LEAK
1. Start engine and run it at idle.
2. Listen for an exhaust gas leak before three way catalyst (manifold).
OK or NG
OK >> GO TO 4.
NG >> Repair or replace.
4.CHECK FOR INTAKE AIR LEAK
Listen for an intake air leak after the mass air flow sensor.
OK or NG
OK >> GO TO 5.
NG >> Repair or replace.
5.CLEAR THE SELF-LEARNING DATA
 With CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Select “SELF-LEARNING CONT” in “WORK SUPPORT” mode with CONSULT-II.
3. Clear the self-learning control coefficient by touching “CLEAR”
or “START”.
4. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to
start engine?
 Without CONSULT-II
1. Start engine and warm it up to normal operating temperature.
2. Turn ignition switch OFF.
3. Disconnect mass air flow sensor (1) harness connector, and
restart and run engine for at least 5 seconds at idle speed.
4. Stop engine and reconnect mass air flow sensor harness con-
nector.
5. Make sure DTC P0102 is displayed.
6. Erase the DTC memory. Refer to EC-47, "
Emission-related
Diagnostic Information".
7. Make sure DTC P0000 is displayed.
8. Run engine for at least 10 minutes at idle speed.
Is the 1st trip DTC P0171 or P0172 detected? Is it difficult to
start engine?
Ye s  o r  N o
Yes >> Perform trouble diagnosis for DTC P0171, P0172. Refer to EC-257or EC-264.
No >> GO TO 6.
PBIB1216E
SEF215Z
BBIA0701E 

EC-232
< SERVICE INFORMATION >
DTC P0133 A/F SENSOR 1
OK >> GO TO 10.
NG >> GO TO 13.
10.CHECK MASS AIR FLOW SENSOR
Refer to EC-173, "
Component Inspection".
OK or NG
OK >> GO TO 11.
NG >> Replace mass air flow sensor.
11 .CHECK PCV VALVE
Refer to EC-43, "
Component Inspection".
OK or NG
OK >> GO TO 12.
NG >> Repair or replace PCV valve.
12.CHECK INTERMITTENT INCIDENT
Perform EC-136
.
OK or NG
OK >> GO TO 13.
NG >> Repair or replace.
13.REPLACE AIR FUEL RATIO (A/F) SENSOR 1
Replace air fuel ratio (A/F) sensor 1.
CAUTION:
• Discard any A/F 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.
• Before installing new A/F sensor, clean exhaust system threads using Oxygen Sensor Thread
Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
>>INSPECTION END
Removal and InstallationINFOID:0000000001702732
AIR FUEL RATIO SENSOR
Refer to EM-21. 

DTC P0137 HO2S2
EC-233
< SERVICE INFORMATION >
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DTC P0137 HO2S2
Component DescriptionINFOID:0000000001702733
The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air/fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-II Reference Value in Data Monitor ModeINFOID:0000000001702734
Specification data are reference values.
On Board Diagnosis LogicINFOID:0000000001702735
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity before the three way catalyst (manifold) causes
the longer switching time. To judge the malfunctions of heated oxy-
gen sensor 2, ECM monitors whether the maximum voltage of the
sensor is sufficiently high during the various driving condition such
as fuel-cut.
DTC Confirmation ProcedureINFOID:0000000001702736
NOTE:
If DTC confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
 WITH CONSULT-II
TESTING CONDITION:
For the best results, perform DTC WORK SUPPORT at a temperature of 0 to 30°C (32 to 86°F).
SEF327R
MONITOR ITEM CONDITION SPECIFICATION
HO2S2  (B1) • Revving engine from idle to 3,000 rpm quickly after the following 
conditions are met.
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 
minute and at idle for 1 minute under no load0 - 0.3V ←→ Approx. 0.6 - 1.0V
HO2S2 MNTR (B1) LEAN ←→ RICH
SEF259VA
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0137
0137Heated oxygen sensor 2 cir-
cuit low voltageThe maximum voltage from the sensor is not 
reached to the specified voltage.• Harness or connectors
(Heated oxygen sensor 2 circuit open or 
shorted.)
• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector
• Intake air leaks 

EC-238
< SERVICE INFORMATION >
DTC P0137 HO2S2
OK or NG
OK >> GO TO 5.
NG >> Repair open circuit or short to ground or short to power in harness or connectors.
5.CHECK HEATED OXYGEN SENSOR 2
Refer to EC-238, "
Component Inspection".
OK or NG
OK >> GO TO 6.
NG >> Replace heated oxygen sensor 2.
6.CHECK INTERMITTENT INCIDENT
Refer to EC-136
.
>>INSPECTION END
Component InspectionINFOID:0000000001702740
HEATED OXYGEN SENSOR 2
 With CONSULT-II
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Select “FUEL INJECTION” in “ACTIVE TEST” mode, and select
“HO2S2 (B1)” as the monitor item with CONSULT-II.
6. Check “HO2S2 (B1)” at idle speed when adjusting “FUEL INJECTION” to ±25%.
“HO2S2 (B1)” should be above 0.68V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)” should be below 0.18V at least once when the “FUEL INJECTION” is −25%.
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.
• Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor
Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
 Without CONSULT-II
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
PBIB1783E
PBIB2534E 

DTC P0137 HO2S2
EC-239
< SERVICE INFORMATION >
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3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Set voltmeter probes between ECM terminal 50 (HO2S2 signal) and ground.
6. Check the voltage when revving up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be above 0.68V at least once during this
procedure.
If the voltage is above 0.68V at step 6, step 7 is not neces-
sary.
7. Keep vehicle idling for 10 minutes, then check voltage. Or check
the voltage when coasting from 80 km/h (50 MPH) in D position
with OD OFF (A/T), D position (CVT) or 3rd gear position (M/T).
The voltage should be below 0.18V at least once during this
procedure.
8. If NG, replace heated oxygen sensor 2.
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.
• Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor
Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
Removal and InstallationINFOID:0000000001702741
HEATED OXYGEN SENSOR 2
Refer to EM-21.
PBIB2996E 

EC-240
< SERVICE INFORMATION >
DTC P0138 HO2S2
DTC P0138 HO2S2
Component DescriptionINFOID:0000000001702742
The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air/fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-II Reference Value in Data Monitor ModeINFOID:0000000001702743
Specification data are reference values.
On Board Diagnosis LogicINFOID:0000000001702744
The heated oxygen sensor 2 has a much longer switching time between rich and lean than the air fuel ratio (A/
F) sensor 1. The oxygen storage capacity before the three way catalyst (manifold) causes the longer switching
time.
MALFUNCTION A
To judge the malfunctions of rear heated oxygen sensor 2, ECM
monitors whether the voltage is unusually high during the various
driving condition such as fuel-cut.
MALFUNCTION B
To judge the malfunctions of heated oxygen sensor 2, ECM monitors
whether the minimum voltage of sensor is sufficiently low during the
various driving condition such as fuel-cut.
SEF327R
MONITOR ITEM CONDITION SPECIFICATION
HO2S2  (B1) • Revving engine from idle to 3,000 rpm quickly after the following 
conditions are met.
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 
minute and at idle for 1 minute under no load0 - 0.3V ←→ Approx. 0.6 - 1.0V
HO2S2 MNTR (B1) LEAN ←→ RICH
PBIB2266E
PBIB2376E 

EC-248
< SERVICE INFORMATION >
DTC P0138 HO2S2
5. Select “FUEL INJECTION” in “ACTIVE TEST” mode, and select
“HO2S2 (B1)” as the monitor item with CONSULT-II.
6. Check “HO2S2 (B1)” at idle speed when adjusting “FUEL INJECTION” to ±25%.
“HO2S2 (B1)” should be above 0.68V at least once when the “FUEL INJECTION” is +25%.
“HO2S2 (B1)” should be below 0.18V at least once when the “FUEL INJECTION” is −25%.
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.
• Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor
Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
 Without CONSULT-II
1. Start engine and warm it up to the normal operating temperature.
2. Turn ignition switch OFF and wait at least 10 seconds.
3. Start engine and keep the engine speed between 3,500 and 4,000 rpm for at least 1 minute under no load.
4. Let engine idle for 1 minute.
5. Set voltmeter probes between ECM terminal 50 (HO2S2 signal) and ground.
6. Check the voltage when revving up to 4,000 rpm under no load
at least 10 times.
(Depress and release accelerator pedal as soon as possible.)
The voltage should be above 0.68V at least once during this
procedure.
If the voltage is above 0.68V at step 6, step 7 is not neces-
sary.
7. Keep vehicle idling for 10 minutes, then check voltage. Or check
the voltage when coasting from 80 km/h (50 MPH) in D position
with OD OFF (A/T), D position (CVT) or 3rd gear position (M/T).
The voltage should be below 0.18V at least once during this
procedure.
8. If NG, replace heated oxygen sensor 2.
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.
• Before installing new oxygen sensor, clean exhaust system threads using Oxygen Sensor
Thread Cleaner tool J-43897-18 or J-43897-12 and approved anti-seize lubricant.
Removal and InstallationINFOID:0000000001702750
HEATED OXYGEN SENSOR 2
PBIB1783E
PBIB2534E
PBIB2996E 

EC-250
< SERVICE INFORMATION >
DTC P0139 HO2S2
DTC P0139 HO2S2
Component DescriptionINFOID:0000000001702751
The heated oxygen sensor 2, after three way catalyst (manifold),
monitors the oxygen level in the exhaust gas.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air/fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-II Reference Value in Data Monitor ModeINFOID:0000000001702752
Specification data are reference values.
On Board Diagnosis LogicINFOID:0000000001702753
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity before the three way catalyst (manifold) causes
the longer switching time. To judge the malfunctions of heated oxy-
gen sensor 2, ECM monitors whether the switching response of the
sensor's voltage is faster than specified during the various driving
condition such as fuel-cut.
DTC Confirmation ProcedureINFOID:0000000001702754
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
 WITH CONSULT-II
TESTING CONDITION:
For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30 °C (32 to 86 °F).
SEF327R
MONITOR ITEM CONDITION SPECIFICATION
HO2S2 (B1) • Revving engine from idle to 3,000 rpm quickly after the following condi-
tions are met.
- Engine: After warming up
- Keep the engine speed between 3,500 rpm and 4,000 rpm for 1 minute 
and idle for 1 minute under no load0 - 0.3V ←→ Approx. 0.6 - 1.0V
HO2S2 MNTR (B1)LEAN ←→ RICH
SEF302U
DTC No. Trouble diagnosis name DTC detecting condition Possible cause
P0139
0139Heated oxygen sensor 2 
circuit slow responseIt takes more time for the sensor to respond be-
tween rich and lean than the specified time.• Harness or connectors
(Heated oxygen sensor circuit is open or 
shorted.)
• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector
• Intake air leaks