Why does the car shake when the oxygen sensor is installed but not when it is unplugged?

[DeRachel]

The reason why the car shakes when the oxygen sensor is installed but not when it is unplugged is that the oxygen sensor is damaged. In this case, you need to go to a 4S shop or auto repair shop to replace the oxygen sensor. Here is the relevant introduction: Effects of a damaged front oxygen sensor on the car: Excessive exhaust emissions; deterioration of engine conditions; engine stalling at idle; inaccurate engine operation and reduced power; the engine computer cannot accurately judge the air-fuel mixture condition; affects the normal operation of the three-way catalytic converter. Function of the oxygen sensor: The automotive oxygen sensor is a key feedback sensor in the electronic fuel injection engine control system. It is a critical component for controlling vehicle exhaust emissions, reducing environmental pollution, and improving the fuel combustion quality of the car engine. Oxygen sensors are installed on the engine exhaust pipe. Maintenance of the oxygen sensor: Check the working condition of the oxygen sensor every 30,000 kilometers. If it shows signs of aging or failure, clean or replace the oxygen sensor promptly.

[VictoriaLynn]

I've driven many cars before and encountered similar oddities with oxygen sensors. When you unplug the oxygen sensor and the car stops shaking, it's because the engine control unit enters a default mode, using fixed values to control fuel delivery, which actually makes it run smoother. But when you plug it back in and it starts shaking, it's most likely a sensor issue—like excessive carbon buildup or internal damage, sending erratic signals that cause the ECU to incorrectly adjust the air-fuel mixture, leading to uneven combustion and engine vibration. Other common causes include aging wiring with poor contact or oil buildup around the sensor. I recommend first trying to clean the sensor port; if it still shakes, replace it. Regular maintenance should include periodic checks of the sensor, as it affects fuel efficiency and emissions. Ignoring the issue for too long could damage other components, so it's best to get a full diagnostic of the wiring at a professional repair shop. Don't underestimate this small part—it plays a crucial role in driving safety and performance when it matters most.

[MacDiana]

I've encountered this oxygen sensor issue while working on my own car. The reason it doesn't shake when unplugged is because the engine control system switches to a basic mode when the sensor is missing, operating relatively stably. But when reinstalled, the shaking indicates a problem with the sensor—it might be dirty, short-circuited, or experiencing signal drift, feeding incorrect data that confuses the computer's air-fuel ratio adjustment, resulting in engine shaking. Common causes include severe carbon buildup on the sensor or loose connectors. Address it promptly as it affects fuel consumption and emissions; try cleaning or replacing it, but don't attempt a DIY fix—get it checked at a reliable repair shop. Regular sensor maintenance while driving can save you a lot of trouble.

[McHarrison]

I've also encountered the issue where the engine doesn't shake when the oxygen sensor is unplugged but shakes when reinstalled. When faulty, it sends incorrect signals, causing the engine computer to adjust fuel improperly, resulting in unstable air-fuel mixture and shaking. After unplugging, the computer uses default values and runs smoothly. Common problems include carbon buildup, contamination, or aging; it's recommended to clean the sensor or replace it, and check the wiring if necessary.