DTC P0138: Notes
DTC P0138 DETECTION CONDITION AND POSSIBLE CAUSES
| DTC P0138 |
Middle/Rear HO2S circuit high input |
| DETECTION CONDITION |
- The PCM monitors input voltage from middle/rear HO2S. If the input voltage from the middle\rear HO2S sensor is above 1.2 V for 0.5 s /0.8 s
, the PCM determines that circuit input is high.
Diagnostic support note
- This is a continues monitor (HO2S).
- MIL illuminates if PCM detects above malfunction condition in two consecutive drive cycles or in one drive cycle while DTC for the same malfunction has been stored in PCM.
- PENDING CODE is available if PCM detects the above malfunction condition during first drive cycle.
- FREEZE FRAME DATA is available.
- DTC is stored in the PCM memory.
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| POSSIBLE CAUSE |
- Middle/Rear HO2S malfunction
- Short to power supply in wiring harness between middle/rear HO2S terminal A and PCM terminal 2R, 2Q
- Middle/Rear HO2S or PCM terminal shorted
- PCM malfunction
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 Courtesy of MAZDA MOTORS CORP.
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