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Discussion Starter #1 (Edited)
Hello, My check engine light came on and the mechanic got this code.... P0172B ... Any ideas?? Google search turned up with nothing. Would low fuel or aftermarket intake cause this code?
 

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Discussion Starter #4
The engine is running lean??? That was the code. Could it have something to do with the aftermarket intake?
 

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i went to autozone and had mine scanned today and got the code PO171. which is a fuel trm bank one condition. the power train control module uses the oxygen sensor to calculate the air/fuel ratio of the engine. the computer has recognized a rich or lean condition on one engine bank only.

probable cause
1 if bank one and two codes set together suspect fuel pressure or MAF sensor
2 oxygen sensor
3 ignition misfire repair
4 fuel injector problem.
 

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Hatch Nation #136
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These lean bank one codes seem like they are normally related to vacuum leaks. Try using an unlit propane torch along the vacuum lines until you hear a change in the idle. That would be your leak.
 

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Hatch Nation #136
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Is your MAF sensor in correctly? Like, is it facing the correct direction, and are there any air leaks around it?

If not, then I doubt it would have anything to do with the CAI, especially if you had reset your ECU to use it.
 

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Discussion Starter #11
Here is what I got from the above link, not sure what the B part of the code would mean.

P0172 - System to Rich (Bank 1) The Adaptive Fuel Strategy continuously monitors the fuel delivery hardware. The test fails when the adaptive fuel tables reach a lean calibrated limit. See Possible Causes for DTC P0171 See Diagnostic Aides for DTC P0171
 

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Hatch Nation #136
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I will look into it today, there is also a major bog starting out in first gear.
That could just be because you drive a Focus. Is it boggier than usual?

Try looking up the code without the "B" on the forum. I know it pops up pretty frequently. Check out what others have done to resolve it.

I'd still say start by checking to make sure that the MAF is right, then check out that you didn't make a leak in the throttle body gasket installing the CAI, then propane torch your vacuum lines. All are free options for diagnosing the problem.
 

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Discussion Starter #13
Hello, Thanks for the heads up. I rep'ed you. I bought the car with the CAI installed so I will check over the install.
 
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