Safety Warning
DIY auto repair can cause serious injury, fire, or vehicle damage. These guides are for informational purposes only. Always follow OEM torque specs, wear PPE, and consult a certified mechanic if you are unsure. You are solely responsible for your safety.
DTC P0139 - O2 Sensor Circuit Slow Response (Bank Sensor 2)
2021 Ford Edge SE, 4WDSECTION DTC P0139 - O2 Sensor Circuit Slow Response (Bank Sensor 2)
WARNING: This page is about a different car, the 2020 Ford F-550 Super Duty, 2020 Ford F-450 Super Duty, 2020 Ford F-350 Super Duty, 2020 Ford F-250 Super Duty, and 2020 Ford F-150. However, it is still accessible from the selected car via links, so may be relevant.
DTC DESCRIPTION P0139 - O2 SENSOR CIRCUIT SLOW RESPONSE (BANK SENSOR 2)
| Description: | The nitrogen oxides bank 1, sensor 2 (NOx12) module monitors the NOx12 sensor oxygen (O2) response time during the transition from an engine load to deceleration fuel shut off (DFSO). This DTC sets when the actual O2 signal value does not reach a predicted O2 signal value within a calibrated amount of time. | ||
| Possible Causes: |
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| Diagnostic Aids: | The presence of this DTC may indicate that the vehicle is operating in derate mode and may experience a loss of power. After repair, the vehicle may still display a system warning message. Drive the vehicle until the system warning message has cleared from the instrument cluster message center. | ||
| Application | Key On Engine Off | Key On Engine Running | Continuous Memory |
| All | GO to PINPOINT TEST RD . | ||
RENDER: 1.0x
NO RELATED
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When to See a Mechanic
Stop DIY work and contact a certified mechanic immediately if any of the following apply:
- • You smell fuel, burning insulation, or see smoke.
- • Brakes feel soft, pull hard to one side, or make grinding noises.
- • The engine overheats, stalls repeatedly, or misfires under load.
- • You are missing required tools, torque specs, or safe lifting equipment.
- • You are not confident in the next step or safety outcome.