P0171 SUZUKI SWIFT 2008 2.G Service Workshop Manual

Downloaded from www.Manualslib.com manuals search engine 1-ii Table of Contents
DTC P0123: Throttle / Pedal Position Sensor / Switch “A” (Main) Circuit High ....................... 1A-85
DTC P0131 / P0132: O2 Sensor (HO2S) Circuit Low Voltage / High Voltage (Sensor-
1) ..................................................................... 1A-88
DTC P0133: O2 Sensor (HO2S) Circuit Slow
Response (Sensor- 1) ...................................... 1A-91
DTC P0134: O2 Sensor (HO2S) Circuit No Activity Detected (Sensor -1) ........................... 1A-92
DTC P0137 / P0138: O2 Sensor (HO2S) Circuit Low Voltage / High Voltage (Sensor-
2) ..................................................................... 1A-94
DTC P0140: O2 Sensor (HO2S) Circuit No Activity Detected (Sensor -2) ........................... 1A-97
DTC P0171 / P0172: Fuel System Too Lean / Rich ................................................................. 1A-98
DTC P0222: Throttle / Pedal Position Sensor / Switch “B” (Sub) Circuit Low ....................... 1A-100
DTC P0223: Throttle / Pedal Position Sensor / Switch “B” (Sub) Circuit High ...................... 1A-102
DTC P0300 / P0301 / P0302 / P0303 / P0304: Random / Multiple Cylin der Misfire Detected
/ Cylinder 1 / Cylinder 2 / Cylinder 3 /
Cylinder 4 Misfire Detected ........................... 1A-105
DTC P0327 / P0328: Knoc k Sensor 1 Circuit
Low / High ..................................................... 1A-107
DTC P0335: Crankshaft Position (CKP) Sensor “A” Circuit .......................................... 1A-109
DTC P0340: Camshaft Position (CMP) Sensor “A” Circuit .......................................... 1A-111
DTC P0350: Ignition Coil Primary / Secondary Circuit ............................................................ 1A-114
DTC P0401 / P0402: Exhaust Gas Recirculation Flow Insufficient Detected /
Excessive Detected ...................................... 1A-116
DTC P0403: Exhaust Gas Recirculation Control Circuit ................... ............................ 1A-118
DTC P0420: Catalyst System Efficiency
below Threshold ................ ............................ 1A-120
DTC P0443: Evaporativ e Emission System
Purge Control Valve Circuit ........................... 1A-122
DTC P0480: Fan 1 (Radiator Cooling Fan) Control Circuit ................... ............................ 1A-124
DTC P0500: Vehicle Speed Sensor “A” Malfunction .................................................... 1A-128
DTC P0532: A/C Refrigerant Pressure Sensor “A” Circuit Low ... ............................... 1A-130
DTC P0533: A/C Refrigerant Pressure Sensor “A” Circuit High ................................. 1A-132
DTC P0601 / P0602 / P0607: Internal Control Module Memory Check Sum Error / Control
Module Programming Error / Control Module
Performance ................................................. 1A-134
DTC P0616: Starter Relay Circuit Low............ 1A-135
DTC P0617: Starter Relay Circuit High ........... 1A-136
DTC P0620: Generator Control Circuit ........... 1A-137
DTC P0625 / P0626: Generator Field Terminal Circuit Low / High . .......................... 1A-139
DTC P1501 / P1502: Electric Load Current Sensor Circuit Low / High . ............................ 1A-141 DTC P1510: ECM Back-Up Power Supply
Malfunction .................................................... 1A-143
DTC P1603: TCM Trouble Code Detected ..... 1A-144
DTC P1674: CAN Communication (Bus Off Error) ............................................................. 1A-145
DTC P1676: CAN Communication (Reception Error for TCM) ............................................... 1A-148
DTC P1678: CAN Communication (Reception Error for BCM) ............................................... 1A-149
DTC P1685: CAN Communication (Reception Error for ABS/ESP ® Control Module) ........... 1A-150
DTC P2101: Throttle Actuator Control Motor Circuit Range / Performance ......................... 1A-152
DTC P2102: Throttle Actuator Control Motor Circuit Low .................................................... 1A-154
DTC P2103: Throttle Actuator Control Motor Circuit High.................................................... 1A-155
DTC P2111 / P2112: Throttle Actuator Control System - Stuck Open / Closed ...................... 1A-156
DTC P2119: Throttle Actu ator Control Throttle
Body Range / Performance ........................... 1A-157
DTC P2122: Throttle / Pedal Position Sensor / Switch “D” (Main) Circuit Low Input............. 1A-159
DTC P2123: Throttle / Pedal Position Sensor / Switch “D” (Main) Circuit High Input ............ 1A-161
DTC P2127: Throttle Pedal Position Sensor / Switch “E” (Sub) Circuit Low Input ................ 1A-164
DTC P2128: Throttle / Pedal Position Sensor
/ Switc
h “E” (Sub) Circuit High Input ............. 1A-166
DTC P2135: Throttle / Pedal Position Sensor / Switch “A”/“B” (Main / Sub) Voltage
Correlation..................................................... 1A-168
DTC P2138: Throttle / Pedal Position Sensor / Switch “D”/“E” (Main / Sub) Voltage
Correlation..................................................... 1A-171
DTC P2227 / P2228 / P2229: Barometric Pressure Circuit Malfunction ......................... 1A-173
Inspection of ECM and Its Circuits .................. 1A-175
ECM Power and Ground Circuit Check........... 1A-194
Fuel Injector Circuit Check .............................. 1A-198
Fuel Pump and Its Circuit Check..................... 1A-200
Fuel Pressure Check....................................... 1A-203
A/C System Circuits Check ............................. 1A-205
Electric Load Signal Circuit Check .................. 1A-209
Radiator Cooling Fan Low Speed Control System Check ............................................... 1A-211
Radiator Cooling Fan High Speed Control System Check ............................................... 1A-213
Repair Instructions ......... .................................1A-216
Idle Speed and IAC Throttle Valve Opening Inspection ...................................................... 1A-216
Special Tools and Equipmen t .........................1A-217
Special Tool .................................................... 1A-217
Aux. Emission Control Devices ............. 1B-1
Diagnostic Information and Procedures ............1B-1
EGR System Inspection ...................................... 1B-1
Repair Instructions ............ ..................................1B-1
EVAP Canister Purge Inspec tion ........................ 1B-1

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Engine
Engine General Information and Diagnosis
Precautions
Precautions on Engine ServiceS7RS0B1100001
CAUTION!
The following information on engine service
should be noted carefully, as it is important in
preventing damage, and in contributing to
reliable engine performance.

• When raising or supporting engine for any reason, do
not use a jack under oil pan. Due to small clearance
between oil pan and oil pump strainer, jacking against
oil pan may cause it to be bent against strainer,
resulting in damaged oil pick-up unit.
• It should be kept in mind , while working on engine,
that 12-volt electrical syste m is capable of violent and
damaging short circuits.
When performing any work where electrical terminals
can be grounded, ground cable of the battery should
be disconnected at battery.
• Any time the air cleaner, throttle body or intake manifold is removed, the intake opening should be
covered. This will protect against accidental entrance
of foreign material which could follow intake passage
into cylinder and cause extensive damage when
engine is started.
Precaution on On-Board Diagnostic (OBD)
System
S7RS0B1100005
There are two types of On -Board Diagnostic (OBD)
system, Euro OBD system and non-Euro-OBD system,
depending on the vehicle specification.
As the diagnosis function is different between these two
types, be sure to fully understand the OBD system
referring to “On-Board Diagnostic System Description”.
OBD System Summary Table
Precautions in Diagnosing TroubleS7RS0B1100002
NOTE
There are two types of OBD system
depending on the vehicle specification.
For details, refer to “Precaution on On-Board
Diagnostic (OBD) System”.

• Don’t disconnect couplers from ECM, battery cable
from battery, ECM ground wire harness from engine
or main fuse before confirming diagnostic information
(DTC, freeze frame data, etc.) stored in ECM memory.
Such disconnection will erase memorized information
in ECM memory.
• Diagnostic information stored in ECM memory can be cleared as well as checke d by using SUZUKI scan
tool or OBD generic scan tool. Before using scan tool,
read its Operator’s (Instruction) Manual carefully to
have good understanding as to what functions are
available and how to use it.
For Euro OBD model it is indistinguishable which
module turns on MIL because not only ECM but also
TCM (A/T model) turns on MIL (For details of on-
board diagnostic system for A/T model, refer to “On-
Board Diagnostic System Description in Section 5A”).
Therefore, check both ECM and TCM (A/T model) for
DTC when MIL lights on.
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.
– OBD generic scan tool displays DTC detected by each of ECM and TCM (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 instructi on 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)
Euro OBD
model Non-Euro-OBD
model
Quantity of DTC
related to engine
control Approx. 80 Approx. 60
Freeze frame
data Available Not available
SUZUKI scan
tool Available Available
OBD generic
scan tool Available Not available

Downloaded from www.Manualslib.com manuals search engine 1A-4 Engine General Information and Diagnosis:
Driving Cycle
A “Driving Cycle” consists of engine startup and engine
shutoff.
2 Driving Cycle Detection Logic
The malfunction detected in the first driving cycle is
stored in ECM memory (in t he form of pending DTC) but
the malfunction indicator lamp does not light at this time.
It lights up at the second detection of same malfunction
also in the next driving cycle.
Pending DTC
Pending DTC means a DTC detected and stored
temporarily at 1 driving cycle of the DTC which is
detected in the 2 driving cycle detection logic.
Freeze Frame Data
ECM stores the engine and driving conditions (in the
form of data as shown in the figure) at the moment of the
detection of a malfunction in its memory. This data is
called “Freeze frame data”.
Therefore, it is possible to know engine and driving
conditions (e.g., whether the engine was warm or not,
where the vehicle was running or stopped, where air/fuel
mixture was lean or rich) when a malfunction was
detected by checking the freeze frame data. Also, ECM
has a function to store each freeze frame data for three
different malfunctions in the order as each malfunction is detected. Utilizing this function,
it is possible to know the
order of malfunctions that ha ve been detected. Its use is
helpful when rechecking or diagnosing a trouble.
Priority of freeze frame data:
ECM has 4 frames where the freeze frame data can be stor ed. The first frame stores the freeze frame data of the
malfunction which was detected first. Howe ver, 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.
[A]: 1st or 2nd in parentheses here represents which position in the order
the malfunction is detected.
[A]
I3RB0A110002-01
Priority Freeze frame data in frame 1
1 Freeze frame data at initial detection of malfuncti
on among misfire detected (P0300 – P0304), fuel
system too lean (P0171) and fuel system too rich (P0172)
2 Freeze frame data when a malfunctio n other than those in “1” is detected
Malfunction detected order Frame
Frame 1 Frame 2 Frame 3 Frame 4
Freeze frame data to be updated 1st freeze frame
data 2nd freeze frame
data 3rd freeze frame
data
No malfunction No freeze frame data
1 P0401 (EGR)
detected Data at P0401
detectionData at P0401
detection
——
2 P0171 (Fuel system)
detected Data at P0171
detectionData at P0401
detectionData at P0171
detection
—
3 P0300 (Misfire)
detected Data at P0171
detectionData at P0401
detectionData at P0171
detectionData at P0300
detection
4 P0301 (Misfire)
detected Data 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-29
) *P0140 O2 sensor (HO2S) circuit no
activity detected (Sensor-2) Output voltage of HO2S-2 is more than specification after
warming up engine. 2 driving
cycles
)
{ *P0171 System too lean Total fuel trim is larger than
specification for specified time
or longer. (Fuel trim towa rd rich side is large.) 2 driving
cycles
)
{ *P0172 System too rich Total fuel trim is smaller th
an specification for specified
time or longer. (Fue l trim toward lean side is large.) 2 driving
cycles
) *P0222 Throttle/pedal position sensor
(sub)/switch “B” circuit low Output voltage of TP sensor (sub) is lower than
specification 1 driving
cycle
) *P0223 Throttle/pedal position sensor
(sub)/switch “B” circuit high Output voltage of TP sensor (sub) is higher than
specification 1 driving
cycle
)
U *P0300 Random/multiple cylinder
misfire detected Misfire of such level as to cause damage to three way
catalyst. *2 driving
cycles
)
U *P0301 /
U *P0302 /
U *P0303 /
U *P0304 Cylinder 1 misfire detected
Cylinder 2 misfire detected
Cylinder 3 misfire detected
Cylinder 4 misfire detected
Misfire of such level as to deteriorate emission but not to
cause damage to three way catalyst.
*2 driving
cycles
) *P0327 Knock sensor 1 circuit low Output voltage of knock sensor is less than specification.1 driving
cycle
) *P0328 Knock sensor 1 circuit high Output volta ge of knock sensor is more than specification.1 driving
cycle
) *P0335 Crankshaft position sensor “A”
circuit No signal of CKP sensor for sp
ecified time even if starting
motor signal is input. 1 driving
cycle
) *P0340 Camshaft position sensor “A”
circuit CMP sensor pulse is out of specification. 1 driving
cycle
) † P0350 Ignition c
oil primary /
secondary circuit Ignition signal is not inputted to monitor circuit 5 times or
more continuously. 1 driving
cycle
)
{ *P0401 Exhaust gas recirculation flow
insufficient detected Difference in intake manifold absolute pressure between
opened EGR valve and closed EGR valve is less than
specification. 2 driving
cycles
)
{ *P0402 Exhaust gas recirculation flow
excessive detected Difference in intake manifold absolute pressure between
opened EGR valve and closed EGR valve is more than
specification. 2 driving
cycles
) *P0403 Exhaust gas recirculation
control circuit Output voltage is different from output command with
more than one pole out of 4 poles. 1 driving
cycle
)
U *P0420 Catalyst system efficiency
below threshold
Output waveforms of HO2S-1 and HO2S-2 are similar. 2 driving
cycles
) *P0443 Evaporative emission system
purge control valve circuit Monitor signal of EVAP canister purge valve is different
from command signal. (circuit open or shorted to ground) 2 driving
cycles
) *P0480 Fan 1 (Radiator cooling fan)
control circuit Monitor signal of radiator cooling fan relay is different from
command signal. 1 driving
cycle
) *P0500 Vehicle speed sensor “A” No VSS signal during fuel cut fo
r specified time or longer,
or VSS signal is not input even if vehicle is driving with
more than specified engine speed and D-range (for A/T
model). 2 driving
cycles
) P0532 A/C refrigerant pressure sensor
“A” circuit low Output voltage of A/C refrigerant pressure sensor is less
than specification.
—
) P0533 A/C refrigerant pressure sensor
“A” circuit high Output voltage of A/C refrigerant pressure sensor is more
than specification.
—
) *P0601 Internal control module
memory check sum error Data write error or check sum error. 1 driving
cycle
) P0602 Control module programming
error Data programming error.
—
) *P0607 Control module performance Data programming error. 1 driving
cycle
)
U *P061

6Starter relay circuit low Starter signal is low voltage even though engine is started
with vehicle at stop. 2 driving
cycles
DTC No. Detecting item
Detecting condition
(DTC will set when detecting:) MIL

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 Engine General Information and Diagnosis: 1A-95
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 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)
• Engine Coolant temperature: 70 °C (158 °F) to 150 °C (302 °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 and clear DTC using scan tool.
3) Start engine and warm up to normal operating temperature.
4) Increase vehicle speed to 70 – 80 km/h (43 – 50 mile/h) at 5th gear or D range.
5) Release accelerator pedal and with engine brake applied, ke ep 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. (Throt tle valve opening is kept constant in this step.)
8) Repeat Step 5).
9) 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 Is 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.
3 HO2S-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 continuous ly 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-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

Downloaded from www.Manualslib.com manuals search engine 1A-98 Engine General Information and Diagnosis:
DTC P0171 / P0172: Fuel System Too Lean / RichS7RS0B1104036
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 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)
• Engine coolant temperature: 40 °C (104 °F) to 120 °C (248 °F)
• Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)

3 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 4. “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.
4 HO2S-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.
5 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 6. Repair HO2S-2 circuit. If
circuit is OK, substitute
a known-good ECM and
recheck.
6 HO2S-2 check
1) Check HO2S-2 referring to “HO2S-1 and HO2S-2
Heater On-Vehicle Inspection in Section 1C”.
Is it in good condition? Substitute a known-
good ECM and recheck.
Replace HO2S-2.
Step Action Yes No
DTC detecting condition
Trouble area
DTC P0171:
Total fuel trim is higher than 35% or short term fuel trim is higher
than 20% for more than 1 min. continuously.
(2 driving cycle detection logic)
DTC P0172:
Total fuel trim is lower than –35% or short term fuel trim is lower
than –20% for more than 1 min. continuously.
(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

Downloaded from www.Manualslib.com manuals search engine Engine General Information and Diagnosis: 1A-99
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 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 Is there DTC(s) other than fuel system (DTC P0171 /
P0172)? Go to applicable DTC
diag. flow.Go to Step 3.
3 Intake system and exhaust system for leakage check
Are intake system and exhaust system in good condition? Go to Step 4.
Repair or replace
defective part.
4 Fuel pressure check
1) Check fuel pressure referring to “Fuel Pressure Check”.
Is check result satisfactory? Go to Step 5.
Repair or replace
defective part.
5 Fuel injectors and its circuit check
1) Check fuel injectors referring to “Fuel Injector Inspection
in Section 1G”.
Is check result satisfactory? Go to Step 6.
Faulty injector(s) or its
circuit.
6 Visual inspection
1) Check MAF sensor and air intake system.
• Objects which block measur ing duct and resistor of
MAF sensor.
• Other air flow which does not pass MAF sensor.
Are they in good condition? Go to Step 7.
Repair or replace
defective part.
7 MAF sensor for performance check
1) With ignition switch turn ed OFF, install scan tool.
2) Start engine and warm up to normal operating temperature.
3) Check MAF value using scan tool (Refer to “Scan Tool Data” for normal value.).
Is each value within specified range? Go to Step 8.
Go to “DTC P0101:
Mass or Volume Air
Flow Circuit Range /
Performance”.
8 ECT sensor for performance check
1) Check ECT sensor referring to Step 3 and 4 of “DTC
P0118: Engine Coolant Temperature Circuit High”.
Is check result satisfactory? Go to Step 9.
Faulty ECT sensor or its
circuit.