* P0171: System Too Lean (Bank 1) This means the air/fuel mixture in Bank 1 (typically the side of the engine where cylinder #1 is located) is too lean – there's too much air and not enough fuel.
* P0174: System Too Lean (Bank 2) This indicates a lean condition in Bank 2 (the other side of the V6 engine).
Having *both* codes indicates a problem that's likely affecting the entire fuel system, rather than something isolated to just one bank. Possible causes include:
* Vacuum leaks: A large vacuum leak anywhere in the intake system will suck in extra air, making the mixture lean. This is a common culprit and often relatively easy to find and repair. Look for cracks in hoses, loose connections, or failing intake manifold gaskets.
* Mass Airflow Sensor (MAF) sensor issue: A faulty MAF sensor provides incorrect air flow readings to the engine computer (ECM), leading to an incorrect fuel mixture. A dirty MAF sensor can also cause this.
* Fuel injector problems: One or more fuel injectors might be clogged or failing, reducing fuel delivery to one or both banks.
* Fuel pressure regulator: A faulty fuel pressure regulator might not be maintaining the correct fuel pressure.
* Fuel pump: A weak or failing fuel pump can't supply enough fuel under demand.
* Oxygen sensor(s): Faulty oxygen sensors (O2 sensors) can provide inaccurate readings to the engine computer, leading to incorrect fuel adjustments. Your Windstar likely has multiple O2 sensors, one for each bank.
What to do:
1. Don't ignore it: Driving with a lean condition can cause damage to your catalytic converter, and potentially other engine components.
2. Get a professional scan: While an OBD-II code reader can tell you the codes, a professional mechanic with a more advanced scanner can often provide more detailed information, including live data that helps pinpoint the problem more accurately.
3. Troubleshooting: A mechanic will likely start by checking for vacuum leaks, inspecting the MAF sensor, and testing fuel pressure before moving on to more complex diagnostics.
It's crucial to have this diagnosed and repaired by a qualified mechanic to avoid further engine damage. Attempting to fix these issues yourself without proper knowledge and tools can be risky.
