DTC P0139 O2 SENSOR CIRCUIT SLOW RESPONSE (BANK 1 SENSOR 2)
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DTC P0139 O
2
SENSOR CIRCUIT SLOW
RESPONSE (BANK 1 SENSOR 2)
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Detect the slow response of rear oxygen sensor.
Judge NG when the Rich → Lean response
diagnosis or Lean → Rich response diagnosis is NG and judge
OK when both response diagnoses are OK.
[Rich → Lean diagnosis
response]
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1.
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When the measured response time is larger than
a threshold, since the A/F ratio is rich, the response time
of the output change of O2 sensor when changing from Rich to Lean
is measured, and it judges with NG, and when small, it judges with
OK.
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2.
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When O2 sensor voltage at the time
of a fuel shut-off in deceleration return is large (rich), it judges
with NG.
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[Lean → Rich diagnosis
response]
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1.
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The response time of output change of O2 sensor
when an A/F ratio changes from Lean to Rich is measured,
and it is referred to as NG when the measured response time is larger
than a threshold.
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2.
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It is referred to as NG when O2 sensor
voltage after recovery of fuel shut-off in deceleration is small
and still small.
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Diagnostic Method
Measure the response time of the output change
of the oxygen sensor when the A/F ratio changes from rich to
lean. And Judge NG when the measured response time is larger than
the threshold value.
(1)
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Atmosphere
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(A)
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Electromotive
force
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(D)
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Lean
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(2)
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Exhaust
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(B)
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Air fuel
ratio
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(E)
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Theoretical
air fuel ratio
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(3)
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Electromotive
force
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(C)
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Rich
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(F)
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Comparative
voltage
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•
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Rich → Lean response diagnosis
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Secondary
Parameters
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Enable
Conditions
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Battery
voltage
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> 10.9
V
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A/F
sub feedback control condition
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Completed
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6
seconds or more fuel shut-off indecel. time
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Experienced
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After
fuel cut
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≥ 2
seconds
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Accumulative
time of rear oxygen heater current
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≥ 60
seconds
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Continuous
time of rear oxygen heater current
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≥ 30
seconds
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Catalyst
warm-up counter
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≥ 8500
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Perform the diagnosis only once when fuel
shut-off in deceleration after rapid acceleration. (Pay attention
to oxygen sensor voltage for the timing of deceleration.)
When the oxygen sensor output voltage changes
from 0.55 V (rich) to 0.25 V (lean), calculate the Min. value of
response time regarded as judgment value while the output varies
from 0.5 V to 0.3 V.
Abnormality Judgment
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1.
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Judge NG when the judgment value is larger
than the threshold value after fuel shut-off in deceleration.
Response time (Diagnosis value) > Threshold
value → Abnormal
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Note
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Variation time
of rear oxygen sensor output voltage is short during fuel shut-off
in deceleration. Carry out the NG judgment only after the fuel shut-off
in deceleration. As for OK judgment, without the condition of fuel shut-off
in deceleration, judge OK if the value is below the threshold value.
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Judge NG when the malfunction criteria below
are completed in 2 seconds after the recovery of fuel shut-off in
deceleration which requires 6 seconds or more.
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2.
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Judge NG when the O2 sensor voltage
after recovery of fuel shut-off in deceleration is large. Judge
NG when fuel shut-off in deceleration is also long (6s or more),
and although carried out the fuel shut-off in deceleration cut return,
when O2 sensor voltage is large (more than 0.55V).
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Judgment
Value
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Malfunction
Criteria
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Threshold
Value
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Shortest
time change from rich (500 mV O
2
output) to lean (300
mV) if voltage reduces from 550 mV to 250 mV.
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> 0.510
milliseconds
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Time when
more than 550 mV
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> 2
seconds
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Time Needed for Diagnosis:
1
time
Malfunction Indicator
Light Illumination:
Illuminates when malfunction occurs in
2 continuous driving cycles.
Normality Judgement
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1.
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Judge Normal when the response time (diagnostic
value) is smaller than threshold (judgment value) when changing
to lean since O2 sensor voltage.
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2.
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A normal judging is not carried out.
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Judgment
Value
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Malfunction
Criteria
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Threshold
Value
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Change
of the shortest time from rich (500 mV02 output), when voltage decreases
from 550 mV to 250 mV to lean (300 mV).
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≤ 0.510
seconds
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•
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When the OK idling cycle was completed 40 times
in a row
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•
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When “Clear Memory” was
performed
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MALFUNCTION
INDICATOR LIGHT CLEAR CONDITION
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•
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When the OK driving cycle was completed 3 times
in a row
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•
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When “Clear Memory” was
performed
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Sub feedback control: Not allowed
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ECM OPERATING
AT DTC SETTING
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•
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Memorize the freeze frame data. (For test mode $02)
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•
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Memorize the diagnostic value and trouble
standard value. (For test mode $06)
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•
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Lean → Rich response diagnosis
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Secondary
Parameters
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Enable
Conditions
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Battery
voltage
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> 10.9
V
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A/F
main feedback control condition
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Completed
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Fuel
cut on deceleration ≥ 6 seconds
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Experienced
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After fuel
cut
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≥ 2
seconds
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Perform the diagnosis only once when fuel
shut-off in deceleration after rapid acceleration. (Pay attention
to oxygen sensor voltage for the timing of deceleration.)
When the oxygen sensor output voltage changes
from 0.25 V (lean) to 0.55 V (rich), calculate the Min. value of
response time regarded as judgment value while the output varies
from 0.3 V to 0.5 V.
Abnormality Judgment
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1.
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Judge NG when the judgment value is larger
than the threshold value after recovery of fuel shut-off in deceleration.
Response time (Diagnosis value) > Threshold
value → Abnormal
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2.
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Judge NG when the O2 sensor voltage
after recovery of fuel shut-off in deceleration is small.
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Judgment
Value
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Malfunction
Criteria
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Threshold
Value
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Shortest
time change from lean (300 mV O
2
output) to rich (500
mV) if voltage reduces from 500 mV to 250 mV.
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> 2
seconds
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Time when
less than 250 mV
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> 120
seconds
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Time Needed for Diagnosis:
1
time
Malfunction Indicator
Light Illumination:
Illuminates when malfunction occurs in
2 continuous driving cycles.
Normality Judgement
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1.
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Judge Normal when the response time (diagnostic
value) is smaller than threshold (judgment value) when changing
to lean since O2 sensor voltage.
Response Time (diagnosis value) ≤ Threshold
value → Normal
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2.
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A normal judging is not carried out.
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Judgment
Value
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Malfunction
Criteria
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Threshold
Value
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Change
of the shortest time from rich (300 mV02 output), when voltage decreases
from 550 mV to 250 mV to lean (500 mV).
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≤ 2
seconds
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•
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When the OK idling cycle was completed 40 times
in a row
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•
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When “Clear Memory” was
performed
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MALFUNCTION
INDICATOR LIGHT CLEAR CONDITION
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•
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When the OK driving cycle was completed 3 times
in a row
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•
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When “Clear Memory” was
performed
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Sub feedback control: Not allowed
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ECM OPERATING
AT DTC SETTING
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•
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Memorize the freeze frame data. (For test mode $02)
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•
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Memorize the diagnostic value and trouble
standard value. (For test mode $06)
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