Does egr valve failure cause the car smoke?

Yes, a failing EGR (Exhaust Gas Recirculation) valve can cause a car to emit smoke, particularly blue or black smoke. When the EGR valve is stuck open or closed, it can lead to incomplete combustion and increased exhaust emissions. This can result in excess oil or unburned fuel entering the exhaust system, producing noticeable smoke. Additionally, a malfunctioning EGR system can cause engine performance issues, which may further contribute to smoke production.