Question about 2004 Ford F150

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I have a 2004 Ford f150 5.4 and I am getting a P0171 code by itself on and off. Whenever check engine light comes on the truck doesn't accelerate steadily but once the light goes off its fine. What co

-truck runs fine when the issue doesn't occur -trucks has issues accelerating when it does -recently changed a few ignition coils -this issue is on and off -doesn't seem to happen at low speeds -no other codes come on

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Code 171 means the O2 sensor is telling the computer the fuel mixture for bank one is too lean. Bank one is the side with cylinder number one. The problem could be the sensor, or something else like an injector that is actually causing the fuel mixture to be lean. The sensor would need to be checked.

Posted on Jul 11, 2013


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Posted on Jan 02, 2017

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SOURCE: Trouble code P2135, and P2106.

I have the same problem on my 06 explorer.
Ford Dealership told me i needed my "electronic throttle body assembly" replaced.
It would cost about $630.

I'm a little hesitant to let them do that service though, because it may not be the whole thing that needs replacing. I'd just look in to getting the Throttle Positioning Sensor replaced.. which would cost a lot less.

Posted on May 24, 2009

  • 15 Answers

SOURCE: engine cuts out or bogs down when accelerating

if the engine light is flashing, it means you have a misfire in one or more cylinders. it is most likely plugs or coil wires.
mine started doing this a few weeks ago. finally got around to changing the plugs today. the cylinder order on fords is easy, passenger side from front to back is 1234, driver side front to back is 5678. my number 4 cylinder had a plug that was collapsed. the metal piece was crushed into the contact, not allowing any spark.

Posted on Jul 13, 2009

  • 54 Answers

SOURCE: I have a P1747 code... sluggish transmission

Code definition is Electronic Pressure Control (EPC) Solenoid. This solenoid is located in the trans pan. Driving the explorer without getting it fixed could also wear down other parts in your transmission!

Posted on Jul 29, 2009

SOURCE: I have a 2004 ford freestar. P0193 code. Replaced

PO193 ---Fuel Rail Pressure Sensor Circuit
High Input (FRP)

Check Fuel Pressure at Rail

Posted on Mar 22, 2011

  • 1 Answer

SOURCE: Missing and stumbling during acceleration

4.2 ltr missing. 2000 truck, f150. Changed plugs, wires. Ran great for 2 weeks. Started again. Changed coils. Got worse. Changed fuel filter, did nothing. Added injector cleaner and fuel cleaner, nothing. Checked EGR, o.k. It is getting worse. Had new gas about the time it all started.

Posted on Jul 08, 2011

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We have codes P0171, P0191, P0174, P2198. The car is sluggish on acceleration and the engine will sometimes die. Sometimes runs fine and then it will have a gallop during acceleration. Cleared check...

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P0171 indicates a lean condition. The most common cause of this is a defective mass air flow sensor. Also check if any vacuum leaks. P0174 OBD-II Trouble Code

Technical Description

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Note: This DTC is very similar to P0171, and in fact your vehicle may show both codes at the same time.



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I have a Hyundai Elantra 2004 sedan. 75,000

Did the 'Check Engine' Light come ON? Whenever the 'CHECK ENGINE' light comes on, the ECU (Engine Control Unit) sets a Diagnostic Trouble Code (DTC). These codes identify the particular engine management system which caused the light to come on.
You'll need to use/find an OBDII (On-Board Diagnostic) Scanner to retrieve any code which have been stored in the ECU computer. Afterward, we might be able to help you DIAGNOSE the problem and perhaps eventually fix the problem.

Aug 10, 2009 | Hyundai Elantra Cars & Trucks

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