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A Freind of mine's son's Explorer has the check engine light on, with the following codes: P0171, P0401, P0174. The P0401 I know is an EGR Code, and the P0171 & P0174 are bank lean codes (Bank 1 & Bank 2). I'm assuming that the codes are all realated; What should we look at first? EGR Valve, DPFE sensor or vacuum lines?
 

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I'd look over all the vacuum lines first. Also make sure all the electrical connections are tight. I had a P0401 when I didn't plug the DPFE harness plug in all the way after my intake swap.
 

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The P0171 & P0174 codes more than likely are lower intake gaskets. I just did the gaskets to my Explorer last month, not too difficult. Is the motor a SOHC or OHV?

Also check out the Explorer forums. Lots of good info in there! :D

http://www.explorerforum.com/forums/index.php

Joe
 

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Check the vacuum lines, connections to those components, and check the fuel pressure. The lean codes can come from several things, and the gaskets are common to do that. But do the checks first, easy and they find or eliminate things.
 

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Discussion Starter #5
The P0171 & P0174 codes more than likely are lower intake gaskets. I just did the gaskets to my Explorer last month, not too difficult. Is the motor a SOHC or OHV?

Also check out the Explorer forums. Lots of good info in there! :D

http://www.explorerforum.com/forums/index.php

Joe
I THINK it's a SOHC motor. Is there any "Surefire" way to fairly quickly determine if it's the intake gaskets?
 

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I THINK it's a SOHC motor. Is there any "Surefire" way to fairly quickly determine if it's the intake gaskets?
Are there any rough idle symptoms? They usually are bad when it first starts up then they seal up. Check the freeze frame data on the codes, it can give you clues when the code was set (coolant and air temps).

But check all your vac tees and elbows too.

There is a kit I believe that takes care of those gaskets.
 

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I THINK it's a SOHC motor. Is there any "Surefire" way to fairly quickly determine if it's the intake gaskets?
I'd check what everyone has mentioned, then go from there. On the Explorer site, it's mentioned to spray carb cleaner around the lower intake where it bolts to the engine to see if there's a change in idle.

Like tbirdguy mentioned, mine had a lousy idle and the MPG wasn't good either. After the tear down began, I found that 3 out of the 12 lower intake bolts were finger tight! :eek: The gaskets looked fine, but I think the loose bolts were causing the code. Replaced everything, now it's fine! :)

Joe
 
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