1A-109 Engine General Information and Diagnosis:
4
HO2S-2 ground check
1) Disconnect connector from HO2S-2 with ignition switch
turned OFF.
2) Check for proper connection to HO2S-2 connector at
“BLK/RED”, “RED”, “GRN” and “PNK” wire terminals.
3) If connections are OK, measure resistance between
“GRN” wire terminal of HO2S-2 connector and engine
ground.
Is resistance less than 3
Ω
?
Go to Step 5.
“GRN” and/or “GRY/
GRN” 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) Disconnect connectors from ECM with ignition switch
turned OFF.
2) Measure resistance between “RED” wire terminal of
HO2S-2 connector and “C37-11” terminal of ECM
connector.
Is resistance less than 3
Ω
?
Go to Step 6.
“RED” 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) Measure resistance between “RED” wire terminal of
HO2S-2 connector and vehicle body ground.
Is resistance infinity?
Go to Step 7.
“RED” wire is shorted to
ground circuit.
7
HO2S-2 signal circuit check
1) Measure voltage between “RED” wire terminal of HO2S-
2 connector and vehicle body ground with ignition switch
turned ON.
Is voltage 0 V?
Go to Step 8.
“RED” 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 / P2195 /
P2196: Fuel System
Too Lean / Rich / Stuck
Lean / Stuck 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 “Heated Oxygen
Sensor (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
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