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2000 ford lightning I have replaced everything that concerns a lean code p0171 and p0174 maf sensor egr feedback sensor fuel regulator ait sensor idle control sensor and yes i checked fuel pressure it is at 30 # at an idle where do i go from here????????

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  • Ford Master
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P0171 OBD-II Trouble Code - System Too Lean (Bank 1)
What does that mean?
Basically this means that an oxygen sensor in bank 1 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.

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), and/or a hesitation/surge on acceleration.

Causes
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 Solutions include:
* In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 if necessary
* Check for a dirty fuel filter and proper fuel pressure


P0174 OBD-II Trouble Code - System Too Lean (Bank 2)
What does that mean?
Basically this means that an oxygen sensor in bank 2 detected a lean condition (too much oxygen in the exhaust). On V6/V8/V10 engines, Bank 2 is generally the side of the engine that doesn't have cylinder #1.

Note: This DTC is very similar to P0171, 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), and/or a hesitation/surge on acceleration.

Causes
A code P0174 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 can 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 solutions include:
* In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 if necessary
* Check for a dirty fuel filter and proper fuel pressure

---------------------------------------------------------------------------------------------------------

A Ford P0171 is a LEAN code fpr cylinder bank 1, and P0174 is a LEAN code for cylinder bank 2. These codes commonly occur on many Ford vehicles, and are set when the powertrain control module (PCM) sees the air/fuel mixture is running too lean (too much air, not enough fuel).

When the Check Engine Light comes on, either one of these codes, or both, may be found when a code reader or scan tool is plugged into the vehicle diagnostic connector. IF the vehicle is driven long enough, typically both codes will be set.

WHAT A LEAN CODE MEANS
A lean fuel condition may exist if the engine is sucking in too much air and/or the fuel system is not delivering enough fuel. If bad enough, a lean fuel condition may cause lean misfire, a rough idle, hesitation or stumble when accelerating, and/or poor engine performance.

Unmetered air can enter the engine through a vacuum leak, a dirty airflow sensor that is not reading airflow accurately, an EGR valve is not closing and is leaking exhaust into the intake manifold, an EGR valve that is allowing too much flow (because the EGR differential pressure sensor that monitors EGR flow is faulty and is under-reporting EGR flow).

If the problem is not enough fuel, the underling cause may be a weak fuel pump, restricted fuel filter, leaky fuel pressure regulator or dirty fuel injectors.

DIRTY MAF SENSOR
One of the most common causes of Ford P0171 and P0174 lean codes is a dirty mass airflow (MAF) sensor. The MAF sensor is located in the air inlet tube Ford MAF sensor just ahead of the throttle body. The MAF sensor should be protected from outside dust and debris by the air filter, but sometimes the air filter doesn't fit real tight inside the housing and allows unfiltered air into the engine. Dirt can stick to the MAF sensor wire and form a coating that slows the response of the sensor to changes in airflow. The MAF sensor can also be contaminated by fuel vapors that back up through the intake manifold and throttle body when the engine is shut off. The vapors can leave a waxy coating on the sensor wire. This causes the MAF sensor to under report airflow, which in turn misleads the powertrain control module (PCM) so it doesn't add enough fuel to maintain a properly balanced air/fuel ratio. As a result, the engine runs lean and sets a P0171 and/or P0174 code (see Ford TSB 98-23-10 for details).

If the MAF is dirty, the fix is easy enough: just clean or replace the MAF sensor. In many instances, the MAF sensor can be successfully cleaned by spraying the sensor element with electronics cleaner. Do not use any other type of cleaner as this may damage the sensor.

Disconnect the air inlet tube just ahead of the sensor, and then spray the electronics cleaner through the screen at the wire element in the center of the little MAF sensor. Let the cleaner soak in for several minutes, then give it another shot of cleaner. Let it sit another five minutes, then reconnect the air inlet tubing and start the engine.

If the lean codes keep coming back, the MAF sensor may have to be replaced if the engine does not have a vacuum leak or fuel delivery problem.

VACUUM LEAKS
Another common cause of Ford P0171 and P0174 ean codes is an engine vacuum leak. Ford TSB 04-17-4 details procedures for checking fuel trim and looking for vacuum leaks.

Ford fuel pressure regulator On 3.8L Fords with a split-plenum intake manifold, the port gaskets and isolator bolt assemblies for the upper plenum can deteriorate over time and leak air, often as a result of oil being sucked into the intake manifold through the PCV system. Also the vacuum hose that connects the fuel pressure regulator to the intake manifold can swell and leak vacuum where the hose connects to the manifold. Ford TSB 03-16-1 says the fix involves several steps: remove the upper manifold plenum and replace the original gaskets and bolts with revised ones, replace the front valve cover with a revised valve cover that reduces the amount of oil vapor sucked into the PCV system, inspect and replace the fuel pressure regulator hose, and finally, reflash the PCM so it is less sensitive to lean fuel conditions.

BAD DPFE SENSOR
Ford p0171 AND p0174 lean codes can also be set by a bad EGR differential pressure sensor. These sensors have a very high failure rate once a vehicle has more than about 60,000 miles on the odometer or is more than five or six years old.

Ford DPFE sensor The DPFE sensor is mounted on the engine, and is attached with two rubber hoses to the tube that routes exhaust gas to the EGR valve. The original equipment sensor has an rectangular aluminum housing about three inches long. Corrosion inside the sensor reduces its sensitivity to EGR flow, causing it to under-report EGR flow. The PCM responds by increasing EGR flow, which may keep the EGR valve open longer than usual creating a lean condition in the engine. Thus, a bad sensor may set a P0401 code (insufficient EGR flow), or it may not set an EGR code but a P0171 and/or P0174 lean code instead.

The cause of the P0401 code in most cases turns out to be a bad DPFE sensor, not an EGR valve problem or an EGR valve that is plugged up with carbon (though this can also set a P0401 code). An aftermarket replacement DPFE sensor costs less than $50 and usually gets rid of not only the P0401 code, but also the P0171 and P0174 codes, too.


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Posted on Jun 04, 2010

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What is Pc171 Code


It's P0171 & P0174 not Pc 171 & Pc174 ! The engine computer has detected a lean condition ! That mean's it's not getting enough fuel or has a vacuum leak , bad O2 sensor ! fuel pump getting weak . fuel pressure regulator weak !
P0171 - System to Lean (Bank 1) The Adaptive Fuel Strategy continuously monitors fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information. Air Measurement System
  • MAF sensor (contaminated, damaged, malfunctioning, etc.)
Fuel System
  • Fuel pressure regulator (leaking, malfunctioning, etc.).
  • Fuel filter plugged, dirty.
  • Fuel pump (weak, check valve leaking, etc.).
  • Leaking/contaminated fuel injectors.
  • Low fuel pressure or running out of fuel.
  • EVAP canister purge valve leaking (when canister is "clean").
  • Fuel supply line restricted.
  • Fuel rail pressure sensor (incorrect reading).
Air Induction System
  • Air leaks after the MAF.
  • Vacuum Leaks.
  • PCV system (leak, valve stuck open, etc.)
  • Improperly seated engine oil dipstick.
Exhaust System
  • Exhaust leaks before or near the HO2Ss (exhaust manifold gasket, mating gaskets, etc.).
EGR System
  • EGR valve tube/gasket leak
  • EVR solenoid vacuum leak
Secondary Air Injection
  • Damaged/malfunctioning secondary air injection system (mechanically stuck valve).
  • P0174 - System to Lean (Bank 2) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a rich calibrated limit. Refer to Section 1 , Powertrain Control Software, Fuel Trim for more information. See Possible Causes for DTC P0171. See Diagnostic Aides for DTC P0171
View Freeze Frame Data to determine operating conditions when DTC was set. Observe LONGFT1 and 2 PID(s). Refer to Section 2 , Adaptive Fuel DTCs Diagnostic Techniques for more information.

Feb 12, 2015 | 2002 Ford Escape

1 Answer

What is p0171 p0174?


P0171 Fuel trim bank one condition Lean (If bank one and two codes set together suspect fuel pressure or MAF sensor. Or O2 sensor defective
P0174Fuel trim bank two condition Lean (same as above or Failed H02S21 Heated O2 sensor Bank 2 sensor 1)

May 11, 2014 | 2000 Jeep Grand Cherokee

1 Answer

Dakota p0171 p0174 taurus


code p0171 refers to system to lean bank 1==causes intake /exhaust leak--AIR system--MAP/MAF sensor--fuel pressure/pump--injectors--HO2s Have a fuel pressure test done on the fuel manifold to check for blocked filter/faulty pump/fuel pressure regulator faults
code p0174 refers to system to lean bank 2 --same causes including hose connection/s
code p0420 refers to catalytic converter system -bank 1 efficiency below threshold==causes catalytic converter--wiring--HO23. Check the cat converter is not cracked inside and the oxygen sensor is working.

Sep 06, 2013 | 2009 Citroen C8 2.0

1 Answer

2000 Ford F 150 Lightning. 5.4 supercharged. Keep


code p0171 refers to system too lean bank 1===causes --intake/ exhaust leak. AIR system---MAF?VAF sensor--fuel pressure/pump--injectors. HO2S
code po174 refers to system too lean bank 2===causes -intake/exhaust leak--fuel pressure /pump--injectors--AIR system---hose connection/s. You have ruled out the fuel pressure and pump so eliminate that from the causes. You have checked the o2 sensors so they can be ruled out. The MAF has been checked so rule that out. You are left with the AIR sensor and VAF sensor. and last the intake/ exhaust leaks. Check the gaskets on the exhaust manifold and the bolts are tight. Check for cracks in the manifold underneath. Check the cat converter for correct operation as that will affect the O2 sensor readings. Lastly if you have replaced any sensors with non genuine items they may be affecting the cpu checking processes and affecting the engine settings for economy. Ford and GMC have a mixture of OB2 and their OEM computer readings so you may have to talk with a ford service department to get that answer for 21

Aug 03, 2013 | Ford F-150 Cars & Trucks

1 Answer

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


Hope this helps; also keep in mind that your feedback is important and I`ll appreciate your time and consideration if you leave some testimonial comment about this answer.

Thank you for using FixYa, have a nice day.

Jul 17, 2012 | Ford Windstar Cars & Trucks

1 Answer

My engine light light is on i took the car to O`REILLY the scan the car and the code is PO171,i just want to know was is that code for


p0171 is system to lean ( bank 1 ). one of the most common causes for a p0171 is a dirty mass air flow sensor ( MAF ). just clean or replace maf sensor. use maf sensor cleaner found at most auto parts stores. do not use any other cleaner. disconnect air tube just ahead of sensor, and then spray the cleaner through the screen at the wire element on the maf sensor,let cleaner soak in for several minutes. then give it another shot of cleaner. let it set another 5 minutes. then reconnect air tube and start engine. or you can follow directions on back of maf spray can. if the lean code comes back, you may have to replace maf sensor. unless you have a vacuum leak. Ford p0171 AND p0174 lean codes can also be set by a bad EGR differential pressure sensor. These sensors have a very high failure rate once a vehicle has more than about 60,000 miles on the odometer or is more than five or six years old. hope this helps !

May 28, 2011 | Ford Escort Cars & Trucks

3 Answers

OBD Codes P0401; P0171; P0174. EGER valve sensor vacuum tube winds up upon starting; will not idle. What have others found to be the issue? EGR sensor has gotten very hot and plastic tube connectors have...


p0401 egr flow insufficient. p0171 system to lean ( bank 1 ). p0174 system to lean ( bank 2 ). common problems that trigger p0401--
  • Restriction in the EGR passages, usually caused by carbon buildup
  • The EGR Valve is defective
  • Lack of proper vacuum or electrical signal to the EGR valve
  • Malfunctioning EGR Vacuum supply solenoid
  • Lack of proper EGR system feedback to the computer from the:
    • Manifold Absolute Pressure Sensor (MAP)
    • Differential EGR Pressure Feedback Sensor (DPFE)
    • EGR Valve Position Sensor (EVP)
    • EGR Temperature Sensor - p0174--
    • In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 also
    • Inspect all vacuum and PCV hoses, replace if necessary
    • Check for a dirty fuel filter and proper fuel pressure p0171- and p0174 are about the same.

Mar 08, 2011 | 2000 Ford Expedition

1 Answer

P0171 and P0174 Left and Right bank lean trouble codes pulled from ECU. Check Engine Light illuminated.


P0171 = system too lean bank 1
P0174 = system too lean bank 2

The fuel/air mixture is too lean for the entire engine. The fuel pump pressure could be too low. The fuel pump pressure regulator could be at fault. There could be an air leak downstream of the MAF sensor. MAF sensor (hot wire type) could be dirty. Check for intake manifold vacuum leaks. The engine coolant temp sensor and/or the intake air temp sensor could be faulty (stuck at full hot mode).

Feb 26, 2011 | 2008 Hyundai Entourage

1 Answer

99 CHEVY trouble shoot code P0171


LEAN TROUBLE CODES (P0171 or P0174) A code P0171 or P0174 indicate the engine is running lean. This means there is too much air and/or not enough fuel. You can confirm the engine is running lean by looking at Short Term Fuel Trim (STFT) and Long Term Fuel Trim (LTFT). Normally, STFT and LTFT should be plus or minus 8 from zero. If STFT and/or LTFT are more than about +10 or higher, it indicates the engine is running LEAN. Negative numbers (-10 or more) indicates the engine is running RICH. A lean fuel condition can be caused by:

* Low fuel pressure due to a weak pump or leaky fuel pressure regulator. (use a fuel pressure gauge to check fuel pressure at idle)

* Dirty fuel injectors. (try cleaning the injectors)

* Vacuum leaks at the intake manifold, vacuum hose connections or throttle body. (Use a vacuum gauge to check for low intake vacuum)

* Leaky EGR valve. (Check operation of EGR valve)

* Leaky PCV Valve or hose. (Check valve and hose connections)

* Dirty or defective Mass Airflow Sensor (MAF). (Try cleaning the MAF sensor wires or filament with aerosol electronics cleaner. Do NOT use anything else to clean the sensor, and do not touch the sensor wires)

______________________________-- Causes 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 Solutions Possible solutions include:
  • In the vast majority of cases, simply cleaning the MAF sensor does the trick. 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 if necessary
  • Check for a dirty fuel filter and proper fuel pressure

Jan 02, 2010 | 2001 Dodge Ram 1500 Truck 2WD

2 Answers

1995 Ford Windstar LX 3.5L Error Codes?


  1. P0171-bank 1 lean, usually oxygen sensor
  2. P0174-bank 2 lean, usually oxygen sensor
  3. PO402-EGR ins. flow, Clean EGR exhaust tubes and replace sensor should fix this problem

Dec 31, 2008 | 1995 Ford Windstar

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