Can bad 02 sensor cause engine smoke?

Yes, a faulty oxygen (O2) sensor can contribute to engine smoke. If the O2 sensor is malfunctioning, it may send incorrect readings to the engine control unit, leading to improper fuel-air mixture. This can result in incomplete combustion, which may cause visible smoke from the exhaust. However, smoke can also be caused by other issues, so it's important to diagnose the problem thoroughly.