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Home >> Mazda >> 2009 >> 5 Touring, 2.3 L >> Repair and Diagnosis >> Engine Performance >> System >> On-Board Diagnostic [Engine Control System L3] >> DTC P0138 [L3] >> Notes

DTC P0138 [L3]: Notes

DTC P0138 (L3) DETECTION CONDITION & POSSIBLE CAUSES

DTC P0138 HO2S circuit high input
DETECTION CONDITION 
  • The PCM monitors input voltage from HO2S. If the input voltage from the HO2S sensor is above 1.2 V  for 0.8 s  , the PCM determines that circuit input is high.

Diagnostic support note 
  • This is a continuous monitor (A/F sensor, HO2S).
  • MIL illuminates if the PCM detects the above malfunction condition in two consecutive drive cycles or in one drive cycle while the DTC for the same malfunction has been stored in the PCM.
  • PENDING CODE is available if the PCM detects the above malfunction condition during the first drive cycle.
  • FREEZE FRAME DATA is available.
  • DTC is stored in the PCM memory.
POSSIBLE CAUSE 
  • HO2S or PCM terminal is shorted
  • Short to power supply in the wiring harness between HO2S terminal A and PCM terminal 2Q
  • HO2S malfunction
  • PCM malfunction
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