I have a 2002 Ford Windstar that is running very badly. Won't idle with stalling. Codes include p0171, p0174, p0305, p0171. It was just running fine, what happened?

SOURCE: 98 E-250 Rough Idle; codes p0156,p1131,p1151,p0301,p0171,p0174+

po301 thru po306 all misfire codes cylinder 1-6 remove plugs and replace them..... set the plug gap first
i suggest u replace the wires also if they never been replaced all these misfire codes can set the others and one is for the oxygen sensor ( 02s or HO2S) CIRCUT MALFUNCTION do u know how to check wireing systems
do the tune up plugs (set gap) .052-.056 change the fuel filter also. clear the codes hows it run
this info is for 98 E-250 4.2Litre
what engine do u have 4.2L or 4.6L i know it is a v-6 by the codes

SOURCE: poor idle dtc P1151, P1131,P0174, P0171. runs ok

Change plugs, and Mass Air Flow sensor. This should do the trick

SOURCE: 2002 ford f150 error codes

a lot of time the 02 sensors are overlooked, it could be numerous things. but check or replace 02 sensors first.

Marvin

• 85242 Answers
• Posted on Jun 27, 2012

SOURCE: ford windstar trouble codes p0171-p0174- p1131-p1151-p0305

All these are fuel trim codes and fuel control O2 sensor related codes, you have something that is causing this as all the sensors seldom fail. My advice here is to see a Ford dealer for the diagnostics before any parts are replaced.

ZJ Limited

• 17989 Answers
• Posted on Jul 17, 2012

SOURCE: Codes P0171, P0174, and P1401

Hi there:
DTC P0171 & P0174 basically this means that an oxygen sensor in bank 1 has detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 1 is the side of the engine that has cylinder #1, Bank 2 is generally the side of the engine that doesn't have cylinder #1. Both code is one of the more common trouble codes.



This code is triggered by the first downstream (front) O2 sensor. The sensor provides a reading of the air:fuel ratio leaving the engine's cylinders, and the vehicles powertrain/engine control module (PCM/ECM) uses that reading and adjusts to keep the engine running at that optimum ratio of 14.7:1. If something is not right and the PCM cannot maintain the 14.7:1 ratio, but rather there is too much air, it triggers this code.


You'll want to also read our article on short and long term fuel trims to help understand the operation of the engine. Note: This DTC is very similar to P0174, and in fact your vehicle may show both codes at the same time.


Symptoms
You will more than likely not notice any drivability problems, although there may be symptoms such as:
a lack of power
detonation (spark knock)
rough idle
hesitation/surge on acceleration.


A code P0171 may mean that one or more of the following has happened:
The MAF (Mass Air Flow) Sensor is dirty or faulty
Note: The use of "oiled" air filters may cause the MAF to become dirty if the filter is over-oiled. There is also an issue with some vehicles where the MAF sensors leak the silicone potting material used to protect the circuitry.
There could be a vacuum leak downstream of the MAF sensor
Possible cracked vacuum or PCV line/connection
Faulty or stuck open PCV valve
Failed or faulty oxygen sensor (bank 1, sensor 1)
Sticking/plugged or failed fuel injector
Low fuel pressure (possible plugged/dirty fuel filter!)
Exhaust leak between engine and first oxygen sensor


Possible Solutions: a lot of times, cleaning the MAF sensor and finding/fixing vacuum leaks fix the problem. If you're on a tight budget, start there, but that may not be the fix for certain. So, possible solutions include:


Clean the MAF sensor. Consult your service manual for it's location if you need help. I find it's best to take it off and spray it with electronics cleaner or brake cleaner. Make sure you are careful not to damage the MAF sensor, and make sure it's dry before reinstalling
Inspect all vacuum and PCV hoses, replace/repair as required
Inspect all hoses and connections in the air intake system
Inspect and/or test the intake manifold gaskets for leakage
Check for a dirty fuel filter and proper fuel pressure
Ideally you'll want to monitor short and long term fuel trims using an advanced scan tool
If you have access, you may want to run a smoke test




DTC P1401 Diff Pres Feedback EGR Circ High Input
Disconnected and plugged vacuum line from EGR valve. Truck ran better.
Put length of hose on EGR valve, turned up 2000 RPM and applied small amount of vacuum (by mouth) and engine started to stall. This would seem to indicate that the EGR valve is working and passages are clear.
Truck seems to run just a little rough. Cleared trouble code


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