What is the P0140 fault code?
3 Answers
P0140 indicates a rear oxygen sensor malfunction. Possible causes include: 1. Sensor circuit malfunction. 2. Sensor itself malfunction. 3. Overly rich air-fuel mixture. 4. Overly lean air-fuel mixture. 5. Damaged or failed three-way catalytic converter. 6. ECM (Engine Control Module) malfunction. Reference information: 1. The oxygen sensor measures oxygen content in engine exhaust to adjust fuel injection, enabling optimal air-fuel ratio. 2. In OBD fault codes, you'll often see references to which bank and which oxygen sensor. Bank 1 refers to the cylinder bank containing cylinder 1, with the remaining bank designated as Bank 2. For either bank, sensor 1 always refers to the upstream oxygen sensor (before catalytic converter), while sensor 2 refers to the downstream oxygen sensor (after catalytic converter).
The P0140 trouble code indicates that the oxygen sensor at Bank 1 Sensor 2 position in your vehicle is not functioning properly. It monitors the oxygen content in the exhaust to help the computer adjust the fuel mixture ratio. If the sensor shows no signal at all, possible causes include a damaged sensor itself, broken wiring, loose or oxidized connectors. This can lead to skyrocketing fuel consumption, excessive exhaust emissions, and may cause the check engine light to stay on. A simple method is to first scan with a diagnostic tool to confirm the fault, then check for dirt or corrosion at the sensor connection points. If cleaning doesn't resolve the issue, often a new sensor replacement is needed. Remember to address it promptly to prevent damage to the catalytic converter. I've dealt with similar issues before, and broken wiring is often the main culprit – something you can fix yourself.
Don't panic when encountering P0140 trouble code - it usually indicates the rear oxygen sensor on the engine's first bank isn't responding. This sensor monitors exhaust emissions. When faulty, you'll notice sluggish acceleration and significantly higher fuel consumption. First, pop the hood and locate the sensor (typically at the rear of the exhaust system), checking for damaged wires or loose connectors. For older vehicles, internal component aging is common. While basic cleaning maintenance can be DIY, replacement is best left to professionals. With a decade of driving experience, I've found similar sensor replacements typically cost around 100+ yuan. Neglecting repairs may lead to environmental compliance issues and minor emission fines - remember, safe driving is what truly matters.
