What cause error code 171 on a ford van?

Error code 171 on a Ford van typically indicates a lean condition in the engine, meaning that the air-fuel mixture is too lean (not enough fuel). This can be caused by issues such as a vacuum leak, faulty fuel injectors, a malfunctioning mass air flow (MAF) sensor, or a clogged fuel filter. Addressing these issues usually involves checking for leaks, inspecting fuel delivery components, and ensuring the MAF sensor is functioning properly. If unresolved, it can lead to reduced performance and increased emissions.