What does the P0 172 code mean?

The P0172 code indicates that the engine control module (ECM) has detected a rich fuel condition in the engine's air-fuel mixture, meaning there is an excess of fuel compared to the amount of air. This can lead to poor fuel economy, increased emissions, and potential engine performance issues. Common causes include a faulty fuel injector, a malfunctioning mass air flow (MAF) sensor, or issues with the fuel pressure regulator. To resolve the issue, a thorough diagnostic is recommended to identify and correct the underlying problem.