P0171 and P0174

Tiny
CAMUMA34
  • MEMBER
  • 2005 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 160,000 MILES
There is a common leak in the intake for this specific truck.
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Sunday, August 14th, 2016 AT 12:55 PM

27 Replies

Tiny
HMAC300
  • EXPERT
Check fuel pressure with a gauge as that can cause it as well auto parts rent it. also check for a vacuum leak.

https://www.2carpros.com/articles/how-to-check-fuel-system-pressure-and-regulator

this guide can help as well

https://www.2carpros.com/articles/repair-lean-mixture-codes-p0171-or-p0174-on-some-manufacturers

Please run down these guides and report back.
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Sunday, August 14th, 2016 AT 1:19 PM
Tiny
WRENCHTECH
  • EXPERT
The PCV line and the main rubber connectors are common causes of lean codes in that truck. Some of them are not easily accessible.
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Sunday, August 14th, 2016 AT 3:26 PM
Tiny
CAMUMA34
  • MEMBER
It was the MAF sensor thanks for the guides helped me fix it
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Sunday, August 14th, 2016 AT 4:12 PM
Tiny
WRENCHTECH
  • EXPERT
Nice work, we are here to help, please use 2CarPros anytime.
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Sunday, August 14th, 2016 AT 4:54 PM
Tiny
MARKLINTY
  • MEMBER
  • 2002 FORD EXPLORER
  • 99,999 MILES
Vehicle had a rough idle for some time. Then I had an overheating problem, the thermostat housing got damaged. Installed a new Housing with a new Thermostat then vehicle started working bad, rough idle and the Chek engine light came on. Had the MAF, Coolant Temp, TPS, Temp Sensors replaced and the Spark plugs and ignition Wires replaced. Worked a little better while it was cold but as it heated up it started working with a rough idle and sometimes cuts off. Whiel checking on it I noticed the Exhaust pipes were Flaming red hot. I removed the Catalytic converter and inspected it, the same thing happened So I replaced the Led wires and the converter stopped Flaming. But the check lights is still on and using a ODB2 I got a P0171 registered. Would the O2 sensor alone solve my problem? Thank you for any help.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
The O2 sensor is what detects how rich or lean the engine is running. I would try that first. Now, for the converter that was red hot. That is usually an indicator that it is plugged. Make sure it is free flowing.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
MTROTTER1961
  • MEMBER
  • 2002 FORD EXPLORER
  • 6 CYL
  • 2WD
  • AUTOMATIC
  • 122,000 MILES
I getting codes po171 & po174, I changed the fuel filter because the truck sits most of the time and reset the codes. This lasted about half a day, It was a daliy driver until a year ago.

When I bought it a egr code came up the first month, so I had a mechanic look at it he cleaned it and it was fine. But that was back in 2006.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
JACOBANDNICKOLAS
  • EXPERT
Both codes are for a lean mixture on both banks. What I recommend is checking for vacuum leaks.

Let me know what you find.

Joe
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
STXHAMMER
  • MEMBER
  • 2002 FORD EXPLORER
  • 4.0L
  • 6 CYL
  • AWD
  • AUTOMATIC
  • 130,000 MILES
I have the SOHC engine. I am getting the following seven codes: P0171, 0174, 0175, 0303, 0304, 0305 and 0306. Any help at all would be appreciated. Thank you in advance. I recently replaced all the spark plugs and was getting 171, 174 and 303. Now I have the above seven codes. Just trying to see where to begin in repairing this rough idle.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
STXHAMMER
  • MEMBER
Additional: rough idle and fuel smell. Where do I start.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
STEVE W.
  • EXPERT
The P0171, P0174, P0175, are all lean codes. First thing would be to check for vacuum leaks, especially at the intake manifold upper/lower junction. The O-rings love to fail and suck in extra air which gives you a lean mix and will give you the codes you have.

P03XX codes are all misfire codes for each cylinder.
If you only had the 303 (cylinder three) code and got the others after a plug change you may want to check the plugs you used and the coils. But do that after you repair the intake leak.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
STXHAMMER
  • MEMBER
Issue resolved! Thank you turns out the number 3 plug was bad, intake hose you mentioned was split and also cleaned the throttle body and she accelerates quicker than ever.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
STEVE W.
  • EXPERT
It's getting to the point that parts stores should have test equipment to test all of the "new" parts as they arrive from the factory. I'm not sure what the current percentage of parts that "failed out of the box" is but it seems to be getting worse.

Good to hear you got it repaired. Vacuum leaks are a real pain. They are extra air that the computer doesn't monitor through the MAF so you get a lean condition.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
BNEEDHAM33
  • MEMBER
  • 2000 FORD EXPLORER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 178,000 MILES
I have a 2000 ford explorer 4.0 OHV. I had 2 codes come up for PO171 and PO174. When I looked them up on google it lead me to believe I needed a intake manifold upper and lower gaskets. After replacing them. I got one of the codes back PO171. Where do I go from here?
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
BLACKOP555
  • EXPERT
Common to get the p0171 code after doing that. If you are not careful putting the manifold back in or dont properly torque down the bolts it will leak. Usually it leak due to improper operation by nicking the orings trying to get manifold back in. Quick check is to start vehicle and spray some propane or brake cleaner around the manifold. If idle changes you found the leak. If not then you may just have a bad o2 sensor or exhaust leak.
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Monday, December 21st, 2020 AT 1:46 PM (Merged)
Tiny
BUCKLEY
  • MEMBER
  • 1999 FORD EXPLORER
  • 141,316 MILES
The cel has been on for 2yrs and my truck runs great it has had the same codes po171 po174 (lean condition banks 1 & 2 ). I need a smog this yr so I need the light off. I have to go to a star station per the state. I couldn't find any vac leaks etc, so I disconnected the bat so it would go out for the smog test. Well I passed all the tests except the function test b-cuz I erased all the monitors needed for that part of the smog test. So the tech told me it was prob the mass airflow sensor, so I spent 130, 00 on a new one while the light was still off I put it on and started a drv cycle to set the monitors so I could get a retest smog. So durning the drv cycle the cel came on same codes so I took the mas back and put the old one back on. I then paid the tech 65.00 to do a diagnostic check to find the prob he found a ever so slight leak in the intake manifold gasket area. So I paid a mechanic to change the gaskets and I barely got the truck home still running great just like always and the friggen light came on again. I'am at my wits end. I have been dealing w/ this since aug 2nd. I have read and watched countless videos I have searched countless sites for ans. All to no avail. However, I have learned alot about mechanics and my truck. But thats not getting the cel off. Do u think maybe the pcm is out of wack since the light has been on so long and the truck has ran great the whole time. I can't find anything wrong cuz there isn't anything wrong except the computer is wack. So can u p. Lease help me find the problem? Nobody else has been able to. I am out of ideas, out of $, out of time and out of my mind w/ this problem and I know more about mechanics then any female should (lol). Oh I almost forgot to mention it may not matter but, then it could be the key to the ans, ( what the hell do I know ) for the 2yrs that the cel was on it showed 2 codes 171 and 174 I know they r related to the lean condition banks 1 &2 but after the intake manifold gaskets got replaced and the light came back on it only showed the po171 code in the stored codes and under the pending codes it showed the 174 code but the total # of codes under diag was 1 code (po171) b-4 it showed 2 total and both were under stored and nothing under pending. So now im all screwed up. I don't know if that makes a bad situation worst or what. Please please please help me.
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Monday, December 21st, 2020 AT 1:47 PM (Merged)
Tiny
SATURNTECH9
  • EXPERT
When he found the leak did he use a smoke machine and do a smoke test to find the vacuum leak?
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Monday, December 21st, 2020 AT 1:47 PM (Merged)
Tiny
BUCKLEY
  • MEMBER
I believe he used carburetor cleaner and he appeared to be very skeptical about finding a leak, like he wasn't quite sure that there was really a leak but he couldn't find any place else that leaked. He even mentioned that he was wrong about it being the mas. The thing is that the gaskets were jacked, torn, glued etc, in the area he thought he detected the leak, yet the cel came back on. With a quickness too. Unlike b-4 it would take 2 drv cycles, this time not even 1. Do u think that part of the prob was corrected by replacing the gaskets, thats y only 1 code p0171 shows and not the po174?
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Monday, December 21st, 2020 AT 1:47 PM (Merged)
Tiny
SATURNTECH9
  • EXPERT
From what you just told me it needs to be smoked to kook for vacuum leaks. Especially since you said the light comes on quicker now.
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Monday, December 21st, 2020 AT 1:47 PM (Merged)
Tiny
MAP1995
  • MEMBER
  • 1997 FORD EXPLORER
  • 6 CYL
  • 4WD
  • AUTOMATIC
  • 269,000 MILES
Hi,

Engine miss during idle and acceleration. Codes p0171, 174 are coming.

Kindly let me know what could be the cause.

Thanks.
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Monday, December 21st, 2020 AT 1:47 PM (Merged)

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