Toyota 4Runner persistent check engine light code P0172 despite replacing fuel injectors on Toyota 4Runner

Some Toyota 4Runner owners report experiencing persistent check engine light code P0172 even after replacing fuel injectors. This issue may arise due to several factors, including the need to check fuel pressure to ensure it is within the specified range, as incorrect pressure can contribute to the problem. Additionally, some owners find that faulty oxygen sensors can lead to a rich air-fuel mixture, triggering the P0172 code. Vacuum leaks in the system are another potential cause that can contribute to this rich condition. Furthermore, inspecting the throttle body and Mass Airflow (MAF) sensor is crucial, as malfunctions in these components can also lead to engine richness. Some owners recommend resetting the Engine Control Unit (ECU) after repairs, which can help clear persistent trouble codes and improve fuel trims. Lastly, maintaining the optimal air-fuel ratio of 14.7:1 is essential for proper engine performance, as the P0172 code indicates an insufficient fuel mixture in the combustion process.