DTC P2251-00: A/F Sensor Negative Current Control Circuit Open: Notes
DETECTION CONDITION AND POSSIBLE CAUSE
| DTC P2251:00 |
A/F sensor negative current control circuit open |
| DETECTION CONDITION |
- The PCM monitors the A/F sensor signal voltage at the PCM terminal 1W. If either of the following conditions are met, the PCM determines that the A/F sensor negative current control circuit is open.
MONITORING CONDITIONS
- Circuit voltage oscillation or the PCM terminal 1W voltage is below 5.3 V
.
- The PCM detects the DTC P0134:00 while the pending code P2251:00 is stored.
- A/F sensor element impedance: specified or more
- Battery voltage: 11-18 V
Diagnostic support note
- This is a continuous monitor (A/F sensor, HO2S).
- The check engine light 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 first drive cycle.
- FREEZE FRAME DATA (Mode 2)/Snapshot data is available.
- The DTC is stored in the PCM memory.
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| FAIL-SAFE FUNCTION |
- Fixes the duty value of the A/F sensor heater.
- Stops the fuel feedback control.
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| POSSIBLE CAUSE |
- A/F sensor connector or terminals malfunction
- PCM connector or terminals malfunction
- Open circuit in wiring harness between A/F sensor terminal D and PCM terminal 1AB
- A/F sensor malfunction
- PCM malfunction
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CAUTION:
- Verify the malfunction symptom according to not only the PID value but also the symptom troubleshooting.
RELATED PIDS
| Monitor item (Definition) |
Unit/Condition |
Condition/Specification (Reference) |
| VSS |
KPH, MPH |
- Displays the vehicle speed
|
| RPM |
RPM |
- Displays the engine speed
|
| O2S11 |
A |
- Idle (after warm up): approx. --39 μA
- Deceleration fuel cut (accelerator pedal released from engine speed of 4,000 rpm or more): approx. 3.84 mA
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