Question about 2004 Ford Freestar

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P0171 and P0174 for 2004 ford freestar ..Van running fine , even after erasing same codes comes back Is it O2 sensor or MAF sensor

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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

  • 260 Answers

SOURCE: Cleaning the Mass Air Flow Sensor

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

  • 301 Answers

SOURCE: I have a 1998 ford explorer odb2 codes of p0171

I would first change the fuel filter.

Posted on Oct 18, 2009

  • 92 Answers

SOURCE: Windstar 2000 3.8. Runs fine. Checked for codes

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

  • 4 Answers

SOURCE: 2000 ford escort ZX2 with P0171 trouble code.

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

L Holland
  • 70 Answers

SOURCE: Trouble code P0171, P2195 Ford Focus

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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1 Answer

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Could be a problem with the MAF sensor but if it is you should have a code for that too.
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For rough idle and error code issues on your ford freestar.Click the link below:----
--------This will help.Thanks.

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P0171 is a lean bank one code. It is usually always a vacuum leak and is usually not an O2 sensor or a MAF sensor. The first step shoul have been to check for vacuum leaks.

What engine do you have?

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Have a van w/ code P0171 and pending P1131. Idea is MAf


P0171 suggests th van is running to lean on bank 1 is the cylinder bank on the RIGHT (passenger side) the plug may be defective or coil damage, no spark.

Is this a gas version or Derv / diesel ? I am assuming it's gas.

DTC P1131 indicates the system is correcting RICH for an overly LEAN condition. In english this means the car's computer is telling the fuel pump to use more fuel (running RICH) because the engine has a low air-fuel mixture (LEAN). The car is out of tune or the airflow sensor, (O2) Heated Oxygen Sensor are worn or are getting an incorrect reading.

So quite rightly it could well be the MAF sensor, and I would look there first. also, try cleaning it with carb cleaner before replacing it, and also look for any air leaks in pipes as again this could cause this.



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Trouble code P0171, P2195 Ford Focus

Even though your O2 sensor is showing good by your scan, it could be lazy in giving readings. It has less than a 10 second window to give the reading especially if it is a heated O2 sensor. Try a Bosch unit.

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The code of p0171 ,how to fix

You can try cleaning the MAF first:

If the code comes back after clearing it, check the spark plugs (not an easy task). My 2000 Expedition had fouled plugs....the 5.4 has a bad head design with recessed spark plugs.

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No overdrive engagement tacoma 2000

Yes, all po codes are a default code, you need to reset the computer by removing the positive cabel for 10 mins.

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