DTC P0139, P0159 HO2S2
EC-265
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DTC P0139, P0159 HO2S2
Component Description
INFOID:0000000001326092
The heated oxygen sensor 2 (HO2S2), after three way catalyst 1,
monitors the oxygen level in the exhaust gas on each bank.
Even if switching characteristics of the air fuel ratio (A/F) sensor 1
are shifted, the air-fuel ratio is controlled to stoichiometric, by the sig-
nal from the heated oxygen sensor 2.
This sensor is made of ceramic zirconia. The zirconia generates volt-
age from approximately 1V in richer conditions to 0V in leaner condi-
tions.
Under normal conditions the heated oxygen sensor 2 is not used for
engine control operation.
CONSULT-III Reference Value in Data Monitor Mode
INFOID:0000000001326093
Specification data are reference values.
On Board Diagnosis Logic
INFOID:0000000001326094
The heated oxygen sensor 2 has a much longer switching time
between rich and lean than the air fuel ratio (A/F) sensor 1. The oxy-
gen storage capacity before the three way catalyst 1 causes the
longer switching time. To judge the malfunctions of heated oxygen
sensor 2, ECM monitors whether the switching response of the sen-
sor's voltage is faster than specified during the various driving condi-
tion such as fuel-cut.
DTC Confirmation Procedure
INFOID:0000000001326095
NOTE:
If DTC Confirmation Procedure has been previously conducted, always turn ignition switch OFF and wait at
least 10 seconds before conducting the next test.
WITH CONSULT-III
TESTING CONDITION:
For better results, perform “DTC WORK SUPPORT” at a temperature of 0 to 30
°
C (32 to 86
°
F).
SEF327R
MONITOR ITEM
CONDITION
SPECIFICATION
HO2S2 (B1)
HO2S2 (B2)
• Revving engine from idle to 3,000 rpm quickly after the following conditions
are met
- Engine: After warming up
- Keeping the engine speed between 3,500 and 4,000 rpm for 1 minute and
at idle for 1 minute under no load
0 - 0.3V
←→
Approx. 0.6 - 1.0V
HO2S2 MNTR(B1)
HO2S2 MNTR(B2)
LEAN
←→
RICH
SEF302U
DTC No.
Trouble diagnosis name
DTC detecting condition
Possible cause
P0139
0139
(Bank 1)
Heated oxygen sensor 2
circuit slow response
It takes more time for the sensor to respond be-
tween rich and lean than the specified time.
• Harness or connectors
(Heated oxygen sensor 2 circuit is open
or shorted)
• Heated oxygen sensor 2
• Fuel pressure
• Fuel injector
• Intake air leaks
P0159
0159
(Bank 2)