DTC Detection Logic
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 oxygen storage capacity of the three way catalyst (manifold) causes the longer switching time.
MALFUNCTION A
To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the voltage is unusually high during the various driving condition such as fuel-cut.
MALFUNCTION B
To judge the malfunctions of heated oxygen sensor 2, ECM monitors whether the minimum voltage of sensor is sufficiently low during the various driving condition such as fuel-cut.
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DTC |
CONSULT screen terms (Trouble diagnosis content) |
DTC detection condition |
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P0138 |
00 |
O2 sensor bank 1 sensor2(B1) (O2 sensor circuit high voltage bank 1 sensor 2) |
A |
Diagnosis condition |
-- |
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Signal (terminal) |
Heated oxygen sensor 2 signal |
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Threshold |
An excessively high voltage from the sensor is sent to ECM |
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Diagnosis delay time |
-- |
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B |
Diagnosis condition |
-- |
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Signal (terminal) |
Heated oxygen sensor 2 signal |
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Threshold |
The minimum voltage from the sensor is not reached to the specified voltage |
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Diagnosis delay time |
-- |
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