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Step
8
Check HO2S–2 heater power circuit.
1) Disconnect connectors from ECM with igni-
tion switch turned OFF.
2) Connect connector to HO2S–2 with ignition
switch turned OFF.
3) Measure resistance between "C64-3" and
"G91-28" wire terminals of ECM connector.
Is resistance below 30 Ω?
DTC P0171 System Too Lean
DTC P0172 System Too Rich
DTC DETECTING CONDITION AND TROUBLE AREA
DTC DETECTING CONDITION
P0171:
Total fuel trim is higher than 43%.
P0172:
Total fuel trim is lower than –30%.
(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 acci-
dent and very careful during testing to avoid occurrence of an accident.
• Road test should be carried out with 2 person, a driver and tester, on a level road.
NOTE:
Check to make sure that the following conditions are satisfied when using this DTC CONFIRMATION
PROCEDURE.
• Intake air temp.: –7°C (19.4°F) or higher
• Engine coolant temp.: –7°C (19.4°F) or higher
• 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) Operate vehicle within freeze frame data condition as noted for 5 min.
5) Stop vehicle and check DTC and pending DTC.
Action
ENGINE GENERAL INFORMATION AND DIAGNOSIS 6-109
Yes
HO2S–2 heater circuit are
OK.
Substitute a known-good
ECM and recheck.
TROUBLE AREA
• Vacuum leaks
• Exhaust gas leakage
• Fuel pressure out of specification
• Fuel injector malfunction
• Heated oxygen sensor–1 malfunction
• MAF sensor malfunction
• ECT sensor malfunction
No
"RED/BLU" wire high
resistance circuit.
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