Question about 1999 Ford Windstar

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Check engine light keeps coming up with same OBD-II codes

PO171 and PO174 "System adaptive fuel too lean (Bank 1)" and "System adaptive fuel too lean (Bank II)" The first time this happend I was told by the Ford dealership that I had an upper intake vaccum leak and that I had to replace the upper intake gasket and the 6 port seals. I did this and my problems went away for about 8 months. Now I'm getting the same codes with the new gaskets. The shop said it could be a Mass Airflow Sensor, but those are expensive if it's not the problem. I've replaced the PCV valve and the fuel filter in the past year. I did new plugs 2 yrs ago and I've installed a K&N air filter. Could my problem just be a leaky hose or something? What would cause both banks to lean out? It has started Idling a little funny at times and it surged the other day. Do I need to dig back into the Intake or is it an MAF sensor? Please help with any tips for diagnosing this problem that you can. Thanks.

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If they did not replace the front valve cover with a new updated one when they did the intake the code will come back.there is a tech service bulletin about this . your mass air flow sensor can be cleaned but would recommend a shop do this.

Posted on Feb 01, 2009

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Po171 po174 code


Lean bank 1 and bank 2 , and throttle actuator system fault. Check reason for lean codes 1st, vacuum leak(s), air inlet boot and hoses, or low fuel pressure / clogged filter. Repair as needed then clear codes and recheck .

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I have a 2004 ford f-150 heritage xlt. check engine light came on and codes are po171 and po174. my book tels me its system adaptive fuel too lean (bank1and2). how should i start my problem solving?


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Check engine light is on and when tested shows codes PO174 and PO171


The P0171 means System too Lean (Bank 1) and P0174 means System too Lean (Bank 2).
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Check engine light is on codes are po171 system too lean (bank 1) po174 system too lean (bank 2) so what can i do


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Generic code PO171 system 2 lean bank 1 generic


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Check Engine light is on my 1997 F150 with a small V-8. The tester returns codes P0171, P0172, P0174 and P0175. What does all this mean?


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1995 Windstar OBD II showing codes PO340, PO171, and PO174.


Symptoms of a faulty Camshaft Position Sensor can include hard starting (or no starting), rough running/misfiring and/or loss of power.

Code 340 COULD be caused solely by a faulty Camshaft Position Sensor. However, this code refers to the entire circuit. So, replacing the sensor may not fix the issue. The problem could lie in any part of the circuit - the sensor itself, the wiring, or the PCM.

Codes 171 and 174 typically appear together. They are caused by the 02 sensors reading too much air (lean) in the exhaust. In most cases, simply cleaning the MAF sensor does the trick. I typically take it off and spray it with electronics or brake cleaner. Just make sure it dries before reinstalling. If this doesn't eliminate the codes, inspect all vacuum and PCV hoses, check for a dirty fuel filter and ensure the furl pressure is within limits.

For clarification, the first trip to the shop your car showed codes 402, 732, 733, 171 and 174. After changing the DPFE/EGR, did ALL those codes go away and now only codes 340, 171 and 174 exist? Or do you have the second set of codes in addition to the first codes?




Jan 15, 2009 | 2001 Ford Windstar

1 Answer

1995 Windstar OBD II showing codes PO340, PO171, and PO174


Hello;
With those codes, the first place I would check is the fuel pressure. Also check the fuel filter and replace it if you haven't already. Then clear codes and recheck. Even if your fuel pressure is with in range it still may not push enough fuel to operate your vehicle.

Jan 15, 2009 | 1995 Ford Windstar

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