Question about 2004 Ford Freestar
Clearing codes is just removing ALL Data
That doesn't do anything more than that
It is not a fix for anything
Type: OBD PO171 & read up on oxygen sensor codes
All vehicle problems & solutions, are are over the internet
All codes are there also, if you know what to type or ask
You need to replace all front oxygen sensors,on all vehicles,
at 100,000 miles
That is preventative maintenance that is not in your owners manual
You learn the hard way, after things fail & continue on, more knowledgeable & proactive in the future
Posted on Mar 20, 2014
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Posted on Jan 02, 2017
i will try to help. 171/174 indicates lean condition in engine. the mass air flow sensor is located in the rubber tube going to throttlebody. you can try to clean it. using mild carb cleaner safe for sensors, remove sensor from tube. spray clean the tiny wires located in the cylinder. do not touch them, they are very delicate. these engines are also notorious for leaking intake gaskets and faulty pcv valves. these will all set these 2 codes. feel free with anymore questions.
Posted on Nov 15, 2008
The upper intake manifold gaskets and isolators (the bolts that hold the manifold down) leak and cause the p0171 and p0174. The reason they leak is due to a missing baffle in the front valve cover which allows some oil into the upper intake which swells the gaskets and wears them. The manifold gaskets and valve cover should be replaced. But before having this done check to see if the black plastic hose on the back of the rubber intake hose(between the throttle body and maf) has dislodged. This happens alot when a new air filter is installed and will cause the same codes.
Posted on Apr 08, 2010
I am working on the same problem. This 2000 ZX2 was idling rough and throwing a p171 code (bank 1 too lean). I hooked up a scanner to the OBDII port and you could see the O2 sensor at 0 or very low voltage and not switching and the fuel compensation maxed out which indicates a lean condition. Using a flammable Carb cleaner and the engine running I sprayed around the vacuum hoses until the idle picked up. I found a rubber elbow that connects to the bottom of the intake maniflold and feeds vacuum to the PCV valve. Replacing the the elbow with a suitable replacment from the auto part misc parts cards display had it running smoothly and the O2 sensor switching properly. Since this was happening at idle it was not the fuel filter which can cause a lean condition in upper rpms. It is not the MAF or the O2 sensor since it switches when not at idle. Also check the smaller vacuum lines that go to the evap control from the intake vacuum ports (back of manifold just below the throttlebody, most will be cracking if your car is anything like mine. I have also seen this problem with a bad PCV valve.
Posted on Jun 14, 2010
Sounds Like your o/2 is bad, are you burning e-8, try adding some injector cleaner/seafoam, and put a tank of preimu gas in then reset the code.
Posted on Jun 27, 2010
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