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Old 12-21-2007, 07:07 PM   #1
eventer289
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Default P1131 and P1151 Codes--Need Help

My car is throwing these codes (right and left bank a/f lean). I cleaned my EGR and my MAF and checked for vacuum leaks, and the codes still come back. I have read that the next step is to replace the front O2 sensors. Is there anything else that would trigger this to happen? The car has not been driven much lately and the battery died while I was driving it. I fixed the corroded terminal clamp by replacing it, but I think the issues are unrelated. It seems to idle kind of rough after a while, and after the SEL came on the RPMS increased to about 1000 at idle for a little bit.

Should I just go ahead and replace the two O2 sensors? I want to make sure before I spend the money.
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Old 12-21-2007, 07:25 PM   #2
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Default RE: P1131 and P1151 Codes--Need Help

You may have an exhaust leak. Check that first.
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Old 12-21-2007, 08:54 PM   #3
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Default RE: P1131 and P1151 Codes--Need Help

I'm throwing the same codes and it started doing it with colder temps. I do have a slight exhaust leak that I will be getting fixed so i'll let ya know how it turns out.
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Old 12-21-2007, 10:07 PM   #4
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Default RE: P1131 and P1151 Codes--Need Help

i had the same exact problem. i would idle rough with the rpms fluctating from 400 to 1000 and it felt really weak. i replaced my MAF, checked for vacuum leaks,replaced the fuel pressure sensor,and replaced my o2 sensors. i let it since in the garage for two monthsuntil this week to fix it (owning multiple cars ftw). i replaced my fuel pump on wednesday and *POOF*, no lean condition. I'd replace the fuel pressure sensor, its the lil black box on the driver's side fuel rail. just $40 from Ford and then the fuel pump (SVT FOCUS ftw) if you still have the condition after replacing the o2 sensors.
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Old 12-22-2007, 01:10 PM   #5
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Default RE: P1131 and P1151 Codes--Need Help

Well unlike you guys were experiencing... I get no rough idle. Car pulls just as hard as it normally does. I suppose I'll look into the exhaust leak first then move on to fuel
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Old 12-22-2007, 01:59 PM   #6
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Default RE: P1131 and P1151 Codes--Need Help

The shop manual says look at the diagnostic tips for P1130--here they are...
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Old 12-22-2007, 02:50 PM   #7
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Default RE: P1131 and P1151 Codes--Need Help

with a bad idle and lean codes it sounds what a vacuum leak to me, just my opinion.
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Old 12-23-2007, 02:11 AM   #8
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Default RE: P1131 and P1151 Codes--Need Help

Is there a way to isolate where the vacuum leak could be?
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Old 12-23-2007, 06:00 AM   #9
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Default RE: P1131 and P1151 Codes--Need Help

You can use a piece of heater hose as a stethoscope--put one end near you ear and run the other around the place where vacuum is available and routed. This may allow you hear the hiss that might otherwise not be audible.[/align][/align]Another way is to use a propane torch, with the gas turned on at a low level but not lit. Play the gas flow over the same areas as described above and listen for increases/changes in idle speed.[/align][/align]Do this is a well-ventilated area, and make 110% sure you have no sparking electrical connections--this is not generally a problem with COP ignition systems, however with wired ignitions you need to make sure the plug wires are properly connected and not old enough to be leaking energy. Open the hood on a car with bad plug wires after dark sometime--often you'll see a pretty good lightshow...[/align]
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Old 12-23-2007, 09:13 AM   #10
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Default RE: P1131 and P1151 Codes--Need Help

i always carefully spray a little fuel injection cleaner around all the vacuum hoses, intake manifold mounting surfaces. when you hit the vacuum leak the idle will usually immediatly change.
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Old 12-23-2007, 09:13 AM
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2002, 2003, 46, bank, code, ford, gt, leak, lean, left, mach1, mustang, p1131, p1151, vacuum

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