What does the P0140 fault code mean?

[GrahamAnn]

P0140 fault code indicates that the oxygen sensor circuit is inactive, specifically the second oxygen sensor in Bank 1. Possible causes of the fault include: 1. Exhaust manifold or exhaust pipe leakage. 2. Fault in the oxygen sensor itself, its circuit, or connector. 3. Fault in the electronic control module (PCM or ECM), etc. Here are some additional considerations: After troubleshooting, the fault code must be cleared promptly. Clearing the fault code should be performed by a professional. Do not attempt to clear the fault code by disconnecting the negative terminal of the battery, as this may cause the vehicle's computer to lose its learned memory, leading to certain functions becoming unavailable, reduced vehicle performance, and potential long-term repair difficulties. Additionally, the fault code may reappear after driving for some time.