Question about 1999 Ford Explorer

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Code #P0171 & code #P0174

1999 ford Explorer XLS with original 65,000 miles
4.0 SOHC 4wd

The codes in the subject line stipulate that bank 1 & 2 are too lean. Replacing the following parts did not fix the problem.

Replaced MAf sensor & check engine light came back on
Replaced right bank & left back 02 sensors & check engine light came back on. The

Please help if you can.......James

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  • dnyswonger Jun 22, 2008

    We are just getting P0171, we have cleaned the maf and reset the code I will come back in a few days Not right away. I have a innova scaner. we did a live data link and took it for a test after we cleaned the maf and reset The only thing that was out of line was the o2s b1 s2 was only going from 0.06 to 0.100 all the other o2 sensors were going from 0.300 to 0.750

  • Anonymous Mar 14, 2014

    A month ago CEL came on for p0171 system too lean bank one CEL turned off by itself next day. Two weeks ago car wouldn't start replaced PEM fixed it! Next day CEL comes on for p0191 fuel rail pressure sensor, so I replace the FRPS. CEL doesn't come back till 10 miles after driving?

  • Anonymous Mar 17, 2014

    I have a 1999 ford f-150 with a P1309 code I'm trying to get inspected. Last year the dealer replaced the cam sensor and synchronized. Said problem was fixed. One day later light came back on and now this year it's the P1309 code. Every year light is on and i am charged large amounts of money only to have light come back on within a day. help

  • Anonymous Mar 19, 2014

    replaced o2 sensors codes and check engine light came back

  • Anonymous Mar 19, 2014

    Codes appear o2 sensor change still check engine light.



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The most common problem on a Ford with these codes is deteriorated PCV hoses. Check the hoses from the PCV valve to the intake manifold. Pay special attention to the rubber elbows. They often crack on the inside curve and the crack is hard to see.

Posted on May 22, 2008


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1 Answer

I would like to know what these codes mean

P0171 System Too Lean (Bank 1)
P0174 System Too Lean (Bank 2)
P0301 Cylinder #1 Misfire Detected
P0302 Cylinder #2 Misfire Detected
P0304 Cylinder #4 Misfire Detected
P0306 Cylinder #6 Misfire Detected

Mar 12, 2014 | 1999 Ford Explorer

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1999 Ford Explorer XLT 4.0 SOHC 4x4 code P1151 bank 1

Ok this is either a shorted wire or bad connector or just plain a bad 02 sensor or a stuck injector or bad PCV needs cleaned. You stated it runs great i would go with Bad 02 sensor first or check for possible exhaust leak and last check for bad converter.

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I have a 98 Ford Contour and these codes. - P0708, P0171, P0442

p0708 is transmission range sensor curcuit high output, p0171 is system to lean ( bank 1 ), p0442 is EVAP emission control leak ( small ).

Mar 20, 2011 | Ford Contour Cars & Trucks

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I am getting a code p0171 and p0174 on my 1999 ford ranger 3.0 liter

P0171 is a LEAN code for cylinder bank 1

P0174 is a LEAN code for cylinder bank 2

That means your car is getting a lot of air and not enough fuel which will make the engine Misfire and rough idle. Well i can say check your mass air flow for any dirt in it and the EGR for any leaks. And also the fuel pump and the fuel lines or any restricted fuel filter. Good luck bro

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Ford explorer ,4 litre. have code of P0171

You could be right but before going to all that trouble of replacing the intake gasket take a close look at the MAF (Mass Air Flow) sensor. Also look for a vacuum leak downstream of the MAF sensor. The MAF sensor may be dirty especially if you are using an "oiled" air filter and it was over oiled. Remove the MAF sensor and clean it with electronic cleaner. Make sure it is dry before reinstalling. If it is damaged, replace it. Also replace the fuel filter as a partially clogged filter has been know to set this code on some vehicles. Check all vacuum hoses and replace as necessary.

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Code #P0171 & code #P0174

Look, man here is the deal:
code p0174 - refer to the front cylinder bank
code p0171 - refer to the rear cylinder bank

Jun 22, 2008 | 2002 Ford Explorer Sport

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