What is the P0140 trouble code?
3 Answers
P0140 trouble code refers to the oxygen sensor circuit inactivity, specifically the second oxygen sensor in the first bank. Here are the relevant details: 1. Possible causes: The causes may include exhaust pipe leakage, malfunction of the oxygen sensor itself or its circuit or connector, or electronic control module failure. During vehicle operation, the ECU continuously monitors the heated oxygen sensor to check its working status in real time. If the heated oxygen sensor signal value remains at the default value, the ECU will command an oscillating air/fuel ratio to attempt to detect changes in the signal value. If the ECU still cannot detect changes in the sensor's signal, this trouble code will appear. 2. Solutions: Take the vehicle to a professional repair shop for inspection. After troubleshooting, the trouble code must be cleared promptly. Clearing the trouble code should be done by professionals and not by disconnecting the negative terminal of the battery. Otherwise, it may cause the car's computer to lose its experiential memory, leading to the malfunction of certain car functions, reduced performance, and increased repair difficulty.
As a new car owner, I've noticed that the P0140 trouble code is quite common. It indicates that there's no signal from the second oxygen sensor circuit in the vehicle, typically located near the rear of the exhaust pipe. This sensor monitors exhaust gases to adjust the fuel mixture ratio. If it malfunctions, it can trigger the check engine light, increase fuel consumption, and even cause poor acceleration. Possible causes include a faulty or aged sensor, wiring damage or short circuits, or loose/corroded connectors. I've tried inspecting it myself - first visually check for any damaged or loose sensor wires. If no obvious issues are found, it's best to visit a repair shop where mechanics can perform a detailed scan. Don't ignore this issue, as prolonged neglect can worsen fuel efficiency and potentially cause emission test failures.
Veteran car enthusiasts know exactly what P0140 means: it indicates that Oxygen Sensor 2 is inactive, located behind the catalytic converter. This component monitors exhaust gases to optimize combustion. Once it fails, it triggers the engine warning light and causes sluggish power response. There are many possible causes, such as the sensor reaching the end of its lifespan, aging or broken wiring harnesses, corroded connectors, or exhaust leaks interfering with the signal. I've encountered this issue while working on my own car. My advice is to first use an OBD scanner to check the data stream—if the voltage doesn't fluctuate, that's a clear confirmation. Then inspect the wiring harness for damage—this can save money on parts and hassle. Repair it promptly to avoid excessive emissions and degraded engine performance.
