Too Lean

[Biniecki]

My explorer just threw a check engine light yesterday and it has been constantly on since. I hooked my scan tool to it tonight and it pulled 3 codes.

1) P0125 - Insufficient Coolant Temperature For Closed Loop Fuel Control

I believe this may have never been cleared after I replaced a faulty thermostat last week.

2) P0171 - Too Lean on Bank 1

3) P0174 - Too Lean on Bank 2

I am just curious as to what I should start checking to try and remedy these codes. I am thinking I may first take a look around the air box as I needed to remove this when I replaced the thermostat. Wondering if its not sealed properly or if the MAF sensor is loose.

 

[rb142]

Look for air leaks. Start with the inlet tubes ... especially anything you had apart. There may be a crack in the tube. Check things like PCV lines. Because it is affecting all of the cylinders (both banks) it should be something upstream of the intake runners. You also need to check that the MAF is working properly. It's getting more air than the MAF says it is. Probably just something simple loose.

 

[blakshukvw]

If this is a 4.0 v6 then you probably need to replace the manifold gaskets.

 

[Biniecki]

It is the 4.0 efi. I checked under the hood the other morning and didn't see much out of place. The boot for the wiring for the MAF sensor was loose. I pushed it back in and cleared the codes. Drove it the other day and codes did not return yet.. Just have to keep an eye on it I guess.

 

[jterry211]

I tried everything and spent lots of money replacing maf, iac, spraying engine down with carb cleaner etc. In the end replaced all the intake lower and upper gaskets and that fixed it.