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.
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HOMESERVICE MANUALSFORD2004MUSTANG BASE, 2D COUPE, 3.9 6, AUTOMATICREPAIR AND DIAGNOSISEXTERNAL PAGESDIFFERENT CARSECTION 2537 (ENGINE CONTROLS - POWERTRAIN DTC CHARTS & DESCRIPTIONS - DTC P0001 THROUGH DTC P0217 - (EXCEPT DIESEL & HYBRID))DTC P0140: O2 CIRCUIT NO ACTIVITY DETECTED (BANK 1, SENSOR 2)
2004 Ford Mustang Base, 2D Coupe, 3.9 6, Automatic
DTC P0140: O2 Circuit No Activity Detected (Bank 1, Sensor 2)
2004 Ford Mustang Base, 2D Coupe, 3.9 6, AutomaticSECTION DTC P0140: O2 Circuit No Activity Detected (Bank 1, Sensor 2)
WARNING: This page does not describe the selected car, but rather 32 other vehicles, including the 2011 Mercury Milan, 2011 Mercury Mariner, 2011 Mercury Grand Marquis, 2011 Lincoln Town Car, and 2011 Lincoln Navigator L. However, it is still accessible from the selected car via links, so may be relevant.
P0140 - O2 CIRCUIT NO ACTIVITY DETECTED (BANK 1, SENSOR 2)
| Description: | The powertrain control module (PCM) monitors the heated oxygen sensor (HO2S) for a lack of movement concern. If the sensor signal value is not changing from the default value, the PCM commands an oscillating air/fuel ratio attempting to detect some movement in the signal value. The test fails when the PCM is unable to detect movement in the sensor signal while the air/fuel ratio is oscillating. | ||
| Possible Causes: |
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| Diagnostic Aids: | An HO2S PID switching across 0.45 volt from 0.2 to 0.9 volts indicates a normal switching HO2S. | ||
| Application | Key On Engine Off | Key On Engine Running | Continuous Memory |
| All | GO to PINPOINT TEST DW . | ||
RENDER: 1.0x
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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.