Table of Contents
Step
3
HO2S heater circuit check
1) Check HO2S heater circuit referring to Step 2 to 4 of
"DTC P0037 / P0038: HO2S Heater Control Circuit Low /
High (Sensor-2, Bank-1)".
Is circuit in good condition?
DTC P0171 / P0172: System Too Lean / Too Rich (Sensor-1, Bank-1)
Wiring Diagram
Refer to "DTC P0030: HO2S Heater Control Circuit (Sensor-1, Bank-1)".
A/F Sensor Description
Refer to "A/F Sensor Description".
DTC Detecting Condition and Trouble Area
DTC detecting condition
DTC P0171:
Total fuel trim (short term fuel trim + long term fuel trim) is higher than
specified range for 10 sec. 3 times.
(2 driving cycle detection logic)
DTC P0172:
Total fuel trim (short term fuel trim + long term fuel trim) is lower than
specified range for 10 sec. 3 times.
(2 driving cycle detection logic)
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 the 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)
• Altitude (barometric pressure): 2400 m, 8000 ft or less (560 mmHg, 75 kPa or more)
• The following DTCs are not detected: DTCs related to MAF sensor, ECT sensor, IAT sensor,
barometric pressure sensor and A/F sensor
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.
Action
Engine General Information and Diagnosis:
Yes
Replace HO2S and
recheck. If this DTC is
detected again,
substitute a known-
good ECM.
• Vacuum leakage
• Exhaust gas leakage
• Fuel pressure out of specification
• Fuel injector
• A/F sensor
• MAF sensor
• ECT sensor
• ECM
1A-81
No
Repair or replace
defective wiring harness
/ connector.
S6RW0C1104033
Trouble area
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Troubleshooting
