P0171 SUZUKI SX4 2006 1.G Service Workshop Manual

Downloaded from www.Manualslib.com manuals search engine 1-ii Table of Contents
DTC P0123: Throttle Position Sensor (Main)
Circuit High ..................................................... 1A-89
DTC P0131 / P0132: O2 Sensor (HO2S)
Circuit Low Voltage / High Voltage (Sensor-
1) ..................................................................... 1A-92
DTC P0133: O2 Sensor (HO2S) Circuit Slow
Response (Sensor-1) ...................................... 1A-95
DTC P0134: O2 Sensor (HO2S) Circuit No
Activity Detected (Sensor-1) ........................... 1A-96
DTC P0137 / P0138: O2 Sensor (HO2S)
Circuit Low Voltage / High Voltage (Sensor-
2) ..................................................................... 1A-98
DTC P0140: O2 Sensor (HO2S) Circuit No
Activity Detected (Sensor-2) ......................... 1A-101
DTC P0171 / P0172: Fuel System Too Lean /
Rich ............................................................... 1A-103
DTC P0222: Throttle Position Sensor (Sub)
Circuit Low .................................................... 1A-105
DTC P0223: Throttle Position Sensor (Sub)
Circuit High ................................................... 1A-107
DTC P0300 / P0301 / P0302 / P0303 / P0304:
Random Misfire Detected / Cylinder 1 /
Cylinder 2 / Cylinder 3 / Cylinder 4 Misfire
Detected ........................................................ 1A-110
DTC P0327 / P0328: Knock Sensor Circuit
Low / High ..................................................... 1A-112
DTC P0335: Crankshaft Position (CKP)
Sensor Circuit ............................................... 1A-114
DTC P0340: Camshaft Position (CMP)
Sensor Circuit ............................................... 1A-116
DTC P0401 / P0402: Exhaust Gas
Recirculation Flow Insufficient Detected /
Excessive Detected ...................................... 1A-119
DTC P0403: Exhaust Gas Recirculation
Control Circuit ............................................... 1A-122
DTC P0420: Catalyst System Efficiency
below Threshold ............................................ 1A-124
DTC P0443: Evaporative Emission System
Purge Control Valve Circuit........................... 1A-126
DTC P0462 / P0463: Fuel Level Sensor
Circuit Low / High .......................................... 1A-128
DTC P0480: Fan 1 (Radiator Cooling Fan)
Control Circuit ............................................... 1A-129
DTC P0481: Cooling Fan 2 (A/C Condenser
Fan) Control Circuit ....................................... 1A-131
DTC P0500: Vehicle Speed Sensor (VSS)
Malfunction .................................................... 1A-134
DTC P0532: A/C Refrigerant Pressure
Sensor Circuit Low ........................................ 1A-136
DTC P0533: A/C Refrigerant Pressure
Sensor Circuit High ....................................... 1A-138
DTC P0601 / P0602 / P0607: Internal Control
Module Memory Check Sum Error / Control
Module Programming Error / Control Module
Performance ................................................. 1A-139
DTC P0616: Starter Relay Circuit Low............ 1A-140
DTC P0617: Starter Relay Circuit High ........... 1A-141
DTC P1510: ECM Back-Up Power Supply
Malfunction .................................................... 1A-143DTC P2101: Throttle Actuator Control Motor
Circuit Range / Performance ......................... 1A-144
DTC P2102: Throttle Actuator Control Motor
Circuit Low .................................................... 1A-146
DTC P2103: Throttle Actuator Control Motor
Circuit High.................................................... 1A-147
DTC P2111: Throttle Actuator Control System
- Stuck Open ................................................. 1A-148
DTC P2119: Throttle Actuator Control Throttle
Body Range / Performance ........................... 1A-149
DTC P2122: Pedal Position Sensor (Main)
Circuit Low Input ........................................... 1A-151
DTC P2123: Pedal Position Sensor (Main)
Circuit High Input........................................... 1A-153
DTC P2127: Pedal Position Sensor (Sub)
Circuit Low Input ........................................... 1A-155
DTC P2128: Pedal Position Sensor (Sub)
Circuit High Input........................................... 1A-158
DTC P2135: Throttle Position Sensor (Main /
Sub) Voltage Correlation ............................... 1A-160
DTC P2138: Pedal Position Sensor (Main /
Sub) Voltage Correlation ............................... 1A-163
DTC P2227 / P2228 / P2229: Barometric
Pressure Circuit Malfunction ......................... 1A-165
DTC U0073: Control Module Communication
Bus Off .......................................................... 1A-166
DTC U0101: Lost Communication with TCM .. 1A-166
DTC U0121: Lost Communication with ABS
Control Module .............................................. 1A-166
DTC U0140: Lost Communication with Body
Control Module .............................................. 1A-166
Troubleshooting for CAN-DTC ........................ 1A-167
Inspection of ECM and Its Circuits .................. 1A-172
ECM Power and Ground Circuit Check........... 1A-193
Fuel Injector Circuit Check .............................. 1A-196
Fuel Pump and Its Circuit Check..................... 1A-198
Fuel Pressure Check....................................... 1A-201
A/C Condenser Cooling Fan Control System
Inspection ...................................................... 1A-202
A/C System Circuits Check ............................. 1A-205
Electric Load Signal Circuit Check .................. 1A-209
Radiator Cooling Fan Control System Check . 1A-211
Repair Instructions ..........................................1A-212
Idle Speed and IAC Throttle Valve Opening
Inspection ...................................................... 1A-212
Special Tools and Equipment .........................1A-213
Special Tool .................................................... 1A-213
Aux. Emission Control Devices ............. 1B-1
Diagnostic Information and Procedures ............1B-1
EGR System Inspection (If Equipped) ................ 1B-1
Repair Instructions ..............................................1B-1
EVAP Canister Purge Inspection ........................ 1B-1
EVAP Canister Purge Valve and Its Circuit
Inspection .......................................................... 1B-1
Vacuum Passage Inspection............................... 1B-2
Vacuum Hose Inspection .................................... 1B-3
EVAP Canister Purge Valve Inspection .............. 1B-3
EVAP Canister Inspection ................................... 1B-4

Downloaded from www.Manualslib.com manuals search engine 1A-2 Engine General Information and Diagnosis:
• When checking ECM for DTC, keep in mind that DTC
is displayed on the scan tool as follows depending on
the scan tool used.
– SUZUKI scan tool displays DTC detected by ECM.
– CAN communication OBD generic scan tool
displays DTC detected by each of ECM and TCM
(for A/T model) simultaneously.
• Priorities for diagnosing troubles
If two or more DTCs are stored, proceed to the DTC
flow which has been detected earliest in the order and
follow the instruction in that flow.
If no instructions are given, troubleshoot DTCs
according to the following priorities.
a. DTCs other than DTC P0171 / P0172 (Fuel
system too lean / too rich), DTC P0300 / P0301 /
P0302 / P0303 / P0304 (Misfire detected) and
DTC P0401 / P0402 (EGR flow malfunction)
b. DTC P0171 / P0172 (Fuel system too lean / too
rich) and DTC P0401 / P0402 (EGR flow
malfunction)
c. DTC P0300 / P0301 / P0302 / P0303 / P0304
(Misfire detected)
• Be sure to read “Precautions for Electrical Circuit
Service in Section 00” before inspection and observe
what is written there.
• ECM replacement:
When substituting a known-good ECM, check for the
following conditions. Neglecting this check may cause
damage to a known-good ECM.
– Resistance value of all relays, actuators is as
specified respectively.
– MAP sensor, A/C refrigerant pressure sensor (if
equipped with A/C), accelerator pedal position
(APP) sensor and TP sensor are in good condition
and none of power circuits of these sensors is
shorted to ground.
• Communication of ECM, BCM, combination meter,
keyless start control module (if equipped with keyless
start control system), 4WD control module (if
equipped), TCM (for A/T model) and ABS control
module, is established by CAN (Controller Area
Network). (For more detail of CAN communication for
ECM, refer to “CAN Communication System
Description”). Therefore, handle CAN communication
line with care referring to “Precaution for CAN
Communication System in Section 00”.
• Immobilizer transponder code registration after
replacing ECM (Immobilizer model)
When ECM is replaced with new one or with another
one, make sure to register immobilizer transponder
code to ECM correctly according to “Procedure after
ECM Replacement in Section 10C”.Precautions for DTC TroubleshootingS6RW0D1100003
• Before performed trouble shooting, be sure to read
the “Precautions of ECM Circuit Inspection”.
• When measuring circuit voltage, resistance and/or
pulse signal at ECM connector, connect the special
tool to ECM and/or the ECM connectors referring 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.
Precautions of ECM Circuit InspectionS6RW0D1100004
• ECM connectors are waterproofed. Each terminal of
the ECM connectors is sealed up with the grommet.
Therefore, when measuring circuit voltage, resistance
and/or pulse signal at ECM connector, do not insert
the tester’s probe into the sealed terminal at the
harness side. When measuring circuit voltage,
resistance and/or pulse signal at ECM connector,
connect the special tool to the ECM connectors. And,
insert the tester’s probe into the special tool’s
connectors at the harness side, and then measure
voltage, resistance and/or pulse signal. Or, ECM and
its circuits may be damaged by water.
• Wire colors of the special tool’s connectors are
different from the ones of the ECM connectors.
However, the circuit arrangement of the special tool’s
connectors is same as the one of the ECM
connectors. Therefore, measure circuit voltage and
resistance by identifying the terminal location subject
to the measurement.
Precautions of Electric Throttle Body System
Calibration
S6RW0D1100005
After performing one of works described below, it is
necessary to re-register the completely closed throttle
valve reference position stored in memory of ECM. (For
detailed information, refer to “Description of Electric
Throttle Body System Calibration”.) For the procedure to
register such data in ECM, refer to “Electric Throttle
Body System Calibration in Section 1C”.
• To shut off backup power of ECM for such purposes of
battery replacement or “DOME” fuse removal
• To erase DTCs P0122, P0123, P0222, P0223, P2101,
P2102, P2103, P2111, P2112, P2119 and/or P2135
• To replace ECM
• To replace throttle body and/or accelerator pedal
position (APP) sensor assembly

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-7
Priority of freeze frame data:
ECM has 4 frames where the freeze frame data can be stored. The first frame stores the freeze frame data of the
malfunction which was detected first. However, the freeze frame data stored in this frame is updated according to the
priority described. (If malfunction as described in the upper square “1” is detected while the freeze frame data in the
lower square “2” has been stored, the freeze frame data “2” will be updated by the freeze frame data “1”.)
In the 2nd through the 4th frames, the freeze frame data of each malfunction is stored in the order as each malfunction
is detected. These data are not updated.
Shown in the table are examples of how freeze frame data are stored when two or more malfunctions are detected.
Freeze frame data clearance:
The freeze frame data is cleared at the same time as clearance of DTC.
Non-Euro-OBD Model
ECM diagnosis troubles which may occur in the area
including the following parts when the ignition switch is
ON and the engine is running, and indicates the result by
turning on malfunction indicator lamp (MIL) (1).
• Heated oxygen sensor-1
• Heated oxygen sensor-2
• ECT sensor
•TP sensor
• Throttle actuator
• MAF sensor
• IAT sensor
• CMP sensor
• CKP sensor
• Knock sensor
• Wheel speed sensor
• CPU (Central Processing Unit) of ECM
• APP sensor
• Oil control valve (VVT model)
• Barometric pressure sensor
• A/C refrigerant pressure sensor
• ECM backup power supply
• Fuel level sensor
•CANECM and MIL operate as follows.
• MIL lights when the ignition switch is turned ON (but
the engine at stop) with the diagnosis switch terminal
ungrounded regardless of the condition of Engine and
Emission control system. This is only to check MIL in
the combination meter and its circuit.
• If the above areas of Engine and Emission control
system is free from any trouble after the engine start
(while engine is running), MIL turns OFF.
• When ECM detects a trouble which has occurred in
the above areas, it makes MIL turn ON while the
engine is running to warn the driver of such
occurrence of trouble and at the same time it stores
the trouble area in ECM back-up memory. (The
memory is kept as it is even if the trouble was only
temporary and disappeared immediately. And it is not
erased unless the power to ECM is shut off for
specified time or it is cleared by SUZUKI scan tool
(SUZUKI-SDT) (2).)
For further detail of the checking / clearing procedure,
refer to “DTC Check” or “DTC Clearance”. Priority Freeze frame data in frame 1
1Freeze frame data at initial detection of malfunction among misfire detected (P0300 – P0304), fuel
system too lean (P0171) and fuel system too rich (P0172)
2 Freeze frame data when a malfunction other than those in “1” is detected
Malfunction detected orderFrame
Frame 1 Frame 2 Frame 3 Frame 4
Freeze frame data to
be updated1st freeze frame
data2nd freeze frame
data3rd freeze frame
data
No malfunction No freeze frame data
1P0401 (EGR)
detectedData at P0401
detectionData at P0401
detection——
2P0171 (Fuel system)
detectedData at P0171
detectionData at P0401
detectionData at P0171
detection—
3P0300 (Misfire)
detectedData at P0171
detectionData at P0401
detectionData at P0171
detectionData at P0300
detection
4P0301 (Misfire)
detectedData at P0171
detectionData at P0401
detectionData at P0171
detectionData at P0300
detection

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-33
) *P0117Engine coolant temperature circuit
lowCircuit voltage of ECT sensor is less than specification.1 driving
cycle
) *P0118Engine coolant temperature circuit
highCircuit voltage of ECT sensor is more than specification.1 driving
cycle
) *P0122Throttle position sensor (main)
circuit lowOutput voltage of throttle position sensor (main) is lower
than specification.1 driving
cycle
) *P0123Throttle position sensor (main)
circuit highOutput voltage of throttle position sensor (main) is higher
than specification.1 driving
cycle
)
U*P0131O2 sensor (HO2S) circuit low
voltage (Sensor-1)Max. output voltage of HO2S-1 is less than specification.2 driving
cycles
)
U*P0132O2 sensor (HO2S) circuit high
voltage (Sensor-1)Min. output voltage of HO2S-1 is more than specification.2 driving
cycles
)
U*P0133O2 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
) *P0134O2 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*P0137O2 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*P0138O2 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
)
U*P0140O2 sensor (HO2S) circuit no activity
detected (Sensor-2)Output voltage of HO2S-2 is more than specification after
warming up engine.
2 driving
cycles
)
U*P0171System too leanTotal fuel trim is larger than specification for specified time
or longer. (Fuel trim toward rich side is large.)2 driving
cycles
)
U*P0172System too richTotal fuel trim is smaller than specification for specified
time or longer. (Fuel trim toward lean side is large.)2 driving
cycles
) *P0222Throttle position sensor (sub) circuit
lowOutput voltage of throttle position sensor (sub) is lower
than specification.1 driving
cycle
) *P0223Throttle position sensor (sub) circuit
highOutput voltage of throttle position sensor (sub) is higher
than specification.1 driving
cycle
)
U*P0300Random misfire detected
Misfire of such level as to cause damage to three way
catalyst or misfire of such level as to deteriorate emission.*2 driving
cycles )U*P030
1 /
U*P0302 /
U*P0303 /
U*P0304Cylinder 1 misfire detected
Cylinder 2 misfire detected
Cylinder 3 misfire detected
Cylinder 4 misfire detected
) *P0327 Knock sensor circuit low Output voltage of knock sensor is less than specification.1 driving
cycle
) *P0328 Knock sensor circuit high Output voltage of knock sensor is more than specification.1 driving
cycle
) *P0335 Crankshaft position sensor circuitNo signal of CKP sensor for specified time even if starting
motor signal is input.1 driving
cycle
) *P0340 Camshaft position sensor circuit CMP sensor pulse is out of specification.1 driving
cycle
)
U*P0401Exhaust gas recirculation flow
detected as insufficientDifference in intake manifold absolute pressure between
opened EGR valve and closed EGR valve is less than
specification.2 driving
cycles
)
U*P0402Exhaust gas recirculation flow
detected as excessive
Difference in intake manifold absolute pressure between
opened EGR valve and closed EGR valve is more than
specification.2 driving
cycles
)
U*P0403Exhaust gas recirculation control
circuitOutput voltage is different from output command with
more than one pole out of 4 poles.1 driving
cycle DTC No. Detecting itemDetecting condition
(DTC will set when detecting:)MIL

Downloaded from www.Manualslib.com manuals search engine 1A-94 Engine General Information and Diagnosis:
4HO2S-1 ground check
1) Disconnect connector from HO2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 connector at
“BLK/RED”, “WHT”, “BLK/WHT” and “ORN” wire
terminals.
3) If connections are OK, measure resistance between
“ORN” wire terminal of HO2S-1 connector and engine
ground.
Is measured resistance less than 5
Ω?Go to Step 5. “ORN” wire is open or
high resistance circuit.
Poor “C01-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
5Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “WHT” wire terminal of
HO2S-1 connector and “C01-10” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 6. “WHT” wire is high
resistance circuit or
open circuit. Poor “C01-
10” terminal connection.
Faulty ECM ground. If
they are OK, substitute
a known-good ECM and
recheck.
6Wire 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.
7HO2S-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.
8HO2S-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.
9Exhaust 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.
10Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-1
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
If DTC still exists,
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-97
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 continuously 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.
3HO2S-1 ground check
1) Disconnect connector from HO2S-1 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-1 at “BLK/RED”,
“WHT”, “BLK/WHT” and “ORN” wire terminals.
3) If wire and connection are OK, measure resistance
between “ORN” wire terminal of HO2S-1 connector and
engine ground.
Is resistance less than 5
Ω?Go to Step 4. “ORN” wire is open or
high resistance circuit.
Poor “C01-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
4Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “WHT” wire terminal of
HO2S-1 connector and “C01-10” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 5. “WHT” wire is high
resistance circuit or
open circuit. Poor “C01-
10” terminal connection
of ECM connector.
Faulty ECM ground. If
they are OK, substitute
a known-good ECM and
recheck.
5Wire 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.
6HO2S-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.
7Exhaust 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. Step Action Yes No

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-99
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 a tester, on a level road.

NOTE
Check to make sure that following conditions are 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)
• Engine Coolant temperature: 70 °C (158 °F) or more
• Altitude (barometric pressure): 2500 m, 8200 ft or less (560 mmHg, 74.4 kPa or more)

1) 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) Increase vehicle speed to 60 – 80 km/h (37 – 50 mile/h) at 5th gear or D range.
5) Release accelerator pedal and with engine brake applied, keep vehicle coasting (with fuel cut for 4 sec. or more),
then stop vehicle and run engine at idle speed for 60 sec. or more.
6) Repeat Step 4).
7) Keep above vehicle speed for 8 min. or more. (Throttle valve opening is kept constant in this step.)
8) Repeat Step 5).
9) Check DTC and pending DTC.
DTC Troubleshooting
NOTE
Before this troubleshooting is performed, read the precautions for DTC troubleshooting referring to
“Precautions for DTC Troubleshooting”.

Step Action Yes No
1Was “Engine and Emission Control System Check”
performed?Go to Step 2. Go to “Engine and
Emission Control
System Check”.
2Is there DTC(s) other than fuel system (DTC P0171 / P0172)
and HO2S-2 (DTC P0140)?Go to applicable DTC
diag. flow.Go to Step 3.
3HO2S-2 and its circuit 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 continuously to enrich A/F mixture and
take foot off from pedal to enlean it).
Does HO2S-2 output voltage indicate deflection between
over 0.35 V and below 0.25 V?Go to “DTC P0171 /
P0172: Fuel System
Too Lean / Rich”.Go to Step 4.

Downloaded from www.Manualslib.com manuals search engine 1A-100 Engine General Information and Diagnosis:
4HO2S-2 ground check
1) Disconnect connector from HO2S-2 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-2 connector at
“RED/BLU”, “BRN”, “ORN” and “BLK/WHT” wire
terminals.
3) If connections are OK, measure resistance between
“ORN” wire terminal of HO2S-2 connector and engine
ground.
Is resistance less than 5
Ω?Go to Step 5. “ORN” wire is open or
high resistance circuit.
Poor “C01-57” terminal
connection. Faulty ECM
ground.
If they are OK,
substitute a known-
good ECM and recheck.
5Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “BRN” wire terminal of
HO2S-2 connector and “C01-11” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 6. “BRN” wire is high
resistance circuit or
open circuit. Poor “C01-
11” terminal connection.
If they are OK,
substitute a known-
good ECM and recheck.
6Wire 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.
7HO2S-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.
8HO2S-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.
9Exhaust 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.
10Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-2
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
Is DTC still exists,
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-102 Engine General Information and Diagnosis:
3Wire circuit check
1) Turn OFF ignition switch.
2) Remove ECM from its bracket with ECM connectors
connected.
3) Measure resistance between “BRN” wire terminal of
HO2S-2 connector and “C01-11” terminal of ECM
connector.
Is resistance less than 5
Ω?Go to Step 4. “BRN” wire is high
resistance circuit or
open circuit. Poor “C01-
11” terminal connection.
If they are OK,
substitute a known-
good ECM and recheck.
4HO2S-2 signal circuit check
1) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure voltage between “BRN” wire terminal of HO2S-
2 connector and vehicle body ground.
Is voltage 0 V?Go to Step 5. “BRN” wire is shorted to
other circuit.
5HO2S-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 6. Repair HO2S-2 circuit. If
circuit is OK, substitute
a known-good ECM and
recheck.
6Exhaust 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.
7Air intake system check
1) Check air intake system for clog or leak.
Is it OK?Replace HO2S-2
referring to “Heated
Oxygen Sensor (HO2S-
1 and HO2S-2)
Removal and
Installation (If Equipped)
in Section 1C”.
If DTC still exists,
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-103
DTC P0171 / P0172: Fuel System Too Lean / RichS6RW0D1104036
DTC Detecting Condition and Trouble Area
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 a tester, on a level road.

NOTE
Check to make sure that following conditions are 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)
• Engine coolant temperature: 70 °C (158 °F) or more
• Altitude (barometric pressure): 2500 m, 8200 ft or less (560 mmHg, 74.4 kPa or more)

1) With ignition switch turned OFF, connect scan tool.
2) Turn ON ignition switch and print Freeze Frame Data or write them down using scan tool.
3) Clear DTC using scan tool.
4) Start engine and warm up to normal operating temperature.
5) Operate vehicle with condition as noted freeze frame data for 5 min.
6) Stop vehicle and check DTC and pending DTC.DTC detecting condition Trouble area
DTC P0171:
Total fuel trim is higher than specified value or short term fuel trim is higher
than specified value for more than 1 min.
(2 driving cycle detection logic)
DTC P0172:
Total fuel trim is lower than specified value or short term fuel trim is lower
than specified value for more than 1 min.
(2 driving cycle detection logic)• Vacuum leakage
• Exhaust gas leakage
• Fuel pressure out of specification
• Fuel injector malfunction
• Heated oxygen sensor-1 malfunction
• MAF sensor malfunction
• ECT sensor malfunction