p0171 andpo174 mean that you're car is running lean
P0171-system too lean bank 1 and P0174-system too lean bank 2
It means your vehicle is running lean you will need to replace the intake manifold gasket, as it is plastic and the seal wears out.
Trouble code P0171 means: Fuel Trim System Lean (Bank 1) Trouble code P0174 means: Fuel Trim System Lean (Bank 2)
Trouble code P0171 means: Fuel Trim System Lean (Bank 1) Trouble code P0174 means: Fuel Trim System Lean (Bank 2)
Trouble code P0171 means: Fuel System Too Lean (Cylinder Bank 1) Trouble code P0174 means: Fuel System Too Lean (Cylinder Bank 2)
Trouble code P0171 means: Fuel System Too Lean (Cylinder Bank 1) Trouble code P0174 means: Fuel System Too Lean (Cylinder Bank 2) These 2 codes are common indicators of a well-known failure on the 1999-2003 Windstars. Be sure to review the additional information in the "Related Questions" below...
Codes P0171 and P0174 indicate that the engine is running lean on both the bank 1 and bank 2 sides, respectively. Common causes include a vacuum leak, such as a cracked or disconnected hose, a dirty or failing mass air flow (MAF) sensor, or issues with the fuel system, such as a clogged fuel filter or weak fuel pump. Additionally, problems with the oxygen sensors can also lead to these codes. It's important to diagnose the specific cause to ensure proper repairs are made.
Error codes P0171 and P0174 indicate that the engine is running too lean on both bank 1 and bank 2, suggesting an imbalance in the air-fuel mixture. Common causes include vacuum leaks, faulty mass air flow (MAF) sensors, or issues with fuel delivery such as clogged fuel injectors or a weak fuel pump. Inspect vacuum hoses for leaks, check the MAF sensor for proper operation, and ensure fuel pressure is within specifications. Addressing these areas can help resolve the lean condition and clear the error codes.
Read through the "Related Question" that discusses a common problem with the Windstars and rough idle - check engine codes P0171 & P0174. That might be part of your problem too...
P0171 - system too lean ( Bank 1 ) - passenger side of engine P0174 - system too lean ( Bank 2 ) - drivers side of engine
P0171, system too lean (bank 1). P0174, system too lean (bank 2). Start with checking for a vacuum leak.