What are the causes of Focus EGR flow failure?
2 Answers
Focus EGR flow failure causes: Poor fuel quality leading to EGR flow failure: The engine has relatively high requirements for fuel quality. Poor fuel quality can cause unclean engine cylinders with deposited carbon buildup, requiring engine carbon cleaning. Sharp temperature drops causing EGR flow failure: During cold starts, especially when temperatures drop sharply, the computer's temperature correction may cause the pollution warning light to illuminate during startup. However, it will stabilize once the temperature drops to a certain level without fluctuations.
Over the years, I've spoken with many Focus owners, and EGR flow faults mainly stem from several aspects. First, issues with the EGR valve itself—over time, it can become stuck or accumulate too much carbon buildup, making the valve's opening and closing less flexible, leading to airflow obstruction or false fault reports. Second, sensor malfunctions, especially if the flow sensor is dirty or broken, can cause the system to misjudge due to inaccurate readings. Third, vacuum tube leaks or disconnections are very common—aging, cracked tubes or loose connections prevent air from being drawn in, affecting the cycle. Fourth, control module problems, such as ECU software bugs or hardware failures, can disrupt signal transmission. Fifth, excessive external carbon buildup—engine exhaust residues clogging the pipes—can cause abnormal pressure and trigger alarms. If you encounter this issue, don't delay; take it to a professional repair shop immediately to avoid long-term increased fuel consumption or excessive emissions. It's recommended to use high-quality fuel and occasionally drive at highway speeds to clear carbon deposits, reducing the likelihood of such problems.
