DTC P2251: Notes
DTC P2251 DETECTION CONDITION AND POSSIBLE CAUSES
| DTC P2251 |
Front HO2S negative current control circuit open |
| DETECTION CONDITION |
- The PCM monitors front HO2S negative current control circuit voltage. If the voltage is not changed against the PCM control value while the engine running, the PCM determines that the front HO2S negative current control circuit is open.
Diagnostic support note
- This is a continuous monitor. (HO2S)
- MIL illuminates if PCM detects the above malfunctioning 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 PCM detects the above malfunction conditions during first drive cycle.
- FREEZE FRAME DATA is available.
- DTC is stored in the PCM memory
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| POSSIBLE CAUSE |
- Front HO2S malfunction
- Connector or terminal malfunction
- Open circuit between PCM terminal 2AC and front HO2S terminal 1B
- Front HO2S heater can not be controlled
- PCM malfunction
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 Courtesy of MAZDA MOTORS CORP.
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