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.
P0140-O2 Sensor 2/2 Circuit High: Notes
- When Monitored : With the engine running between 1000 and 2000 RPM, engine load between 15% to 50%, closed loop mode, the three way catalytic converter temperature is greater than 380°C (716°F), and the O2 sensor heater must be ON for at least 220 seconds to enable the signal inactive portion of the test.
- Set Condition : The high limit: O2 Sensor voltage is greater than 1.5 volts for approximately 5 seconds.
| Possible Causes |
| O2 SENSOR SIGNAL CIRCUIT SHORT TO VOLTAGE |
| ENGINE EXHAUST LEAK |
| O2 SENSOR |
| POWERTRAIN CONTROL MODULE |
For a complete Powertrain Control Module Circuit Diagram, refer to SCHEMATICS AND DIAGRAMS .
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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.
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