What does po171 po181 mean?

The PO171 and PO181 codes refer to diagnostic trouble codes (DTCs) related to vehicle emissions and fuel system performance. Specifically, PO171 indicates a "System Too Lean (Bank 1)," meaning the engine is receiving too much air or not enough fuel, while PO181 relates to "Fuel Composition Sensor Range/Performance Problem," indicating issues with the fuel composition sensor's readings. Both codes can trigger the check engine light and may require further diagnosis to determine the underlying issues, such as vacuum leaks, fuel delivery problems, or sensor malfunctions.