P0171 & P0174
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Senior User
Joined: Feb 2004
Posts: 253
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From: Marietta, GA
P0171 & P0174
Hi all. I know this has been discussed more than a few times, but since the site search is down, I can't find it.
I went to Autozone & had my codes read, since my check engine light came on (again) last night. It came up with P0171 & P0174. According to their guide, since it's both banks that are lean, the first thing I should look at is the MAF, with fuel pressure being second, then O2 Sensors. I asked them about the fuel pressure gauge & they said the one they sell will only go up to 15 lbs which was not enough for the X, which should be at 20-25 lbs.
When the light first came on, about a week ago, it was the day after the last hurricane went through. The night of the storm, I drove through some pretty high water, at least up to the bottom of the doors. I had no problems getting through & no issues until the check engine light came on the next day, while everything was dry & I was on the Interstate. I reset it and it was fine for a few days. Things were a bit chilly last night & it came on again.
The only thing that has changed recently, and it was fine until the CE light came on, was that I put in a permanent drop-in air filter (not a FIPK, just the OEM replacement that goes in the stock airbox).
Any suggestions on where to start?
I went to Autozone & had my codes read, since my check engine light came on (again) last night. It came up with P0171 & P0174. According to their guide, since it's both banks that are lean, the first thing I should look at is the MAF, with fuel pressure being second, then O2 Sensors. I asked them about the fuel pressure gauge & they said the one they sell will only go up to 15 lbs which was not enough for the X, which should be at 20-25 lbs.
When the light first came on, about a week ago, it was the day after the last hurricane went through. The night of the storm, I drove through some pretty high water, at least up to the bottom of the doors. I had no problems getting through & no issues until the check engine light came on the next day, while everything was dry & I was on the Interstate. I reset it and it was fine for a few days. Things were a bit chilly last night & it came on again.
The only thing that has changed recently, and it was fine until the CE light came on, was that I put in a permanent drop-in air filter (not a FIPK, just the OEM replacement that goes in the stock airbox).
Any suggestions on where to start?
Posting Guru
Joined: Aug 2000
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Jon, you're correct in that the first thing to check with these codes is the MAF. If it's dirty, the PCM "sees" less air entering, and reduces the injector pulse width accordingly. This gives a lean mixture. Since the lean code is on both banks, I doubt if it's the O2 sensors fault. Low fuel pressure is always a possibility, as is an intake vacuum leak, but I'd clean the MAF first........
New User
Joined: Aug 2005
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Need to check pvc line
Please check pvc line. I had the same codes and ruff idle when at a stop. I checked the line and found that the rubber grommet that connects the plastic hose to the intake manafoild had hole on the inside. please check this very well because it is easy to miss. You can find the part to replace this grommet at Advanced auto for $2.59 part number 47028. the part is made by MotorMite a division of R&B inc in PA.
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Nice first post, way to jump in from the get go!
We are happy you have chosen the best source for Fords!
Enjoy FTE....and
JOIN CLUB FTE -SUPPORT THE FORUMS!
…..See you on the boards.
