What does the P0140 fault code mean?
2 Answers
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.
I've been driving for decades and have encountered the P0140 trouble code quite a few times. It indicates no activity detected in the oxygen sensor circuit, specifically referring to the downstream oxygen sensor in the exhaust system. Possible causes include aging or failure of the sensor itself, short circuits or open circuits in the wiring harness, or corrosion and looseness in the connectors. This can lead to abnormal monitoring of the emission system, increased fuel consumption, and possibly black smoke issues. It's essential to promptly check whether the sensor plug is secure and if the wiring is worn or disconnected. A simple method is to use a diagnostic tool to see if the voltage readings are normal. If the readings are too low or there's no signal, replacing the sensor should be considered. Never ignore this issue, as it could damage the catalytic converter, leading to more expensive repairs. For those who are handy, it's advisable to perform a self-check first; if that doesn't resolve the issue, take it to a repair shop.
