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Dan107

Fault Code 2012 MP8

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Hello all!  I am a new O/O with a 2012 Mack Pinnacle CXU13 MP8.  The truck has been doing really well, but a few days ago dropped code sa0 spn3471 fmi7.  From what I've found it has something to do with the 7th injector fuel pressure??  Could someone please point me in the right direction to fix this as I don't want this to cascade into something worse!  Thanks in advance.  

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Its the square module that is mounted directly behind the ECU towards the fire wall.  It has a pressure sensor in the top of it that can be change out.  Sometime though, the whole module may need replaced along with the sensor. Also make sure your fuel supply inlet isn't clogged with debris, which can reduce pressure.

If you don't replace this, eventually you will clog the DPF and a regen will be prohibited.   

 

SPN3471 FMI 7  = After treatment injection shut-off valve, Shut off valve stuck,  AHI fuel pressure too low.

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58 minutes ago, 64C85 said:

Its the square module that is mounted directly behind the ECU towards the fire wall.  It has a pressure sensor in the top of it that can be change out.  Sometime though, the whole module may need replaced along with the sensor. Also make sure your fuel supply inlet isn't clogged with debris, which can reduce pressure.

If you don't replace this, eventually you will clog the DPF and a regen will be prohibited.   

 

SPN3471 FMI 7  = After treatment injection shut-off valve, Shut off valve stuck,  AHI fuel pressure too low.

Am I looking in the right place?

AE759B19-3F33-4801-A821-F304E7D77A6F.jpeg

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I've been replacing a lot of the AHD (aftertreatment hydrocarbon doser) modules lately because of oil contamination in the air line to the module. The oil contamination causes the shut off valve inside the AHD module to fail. Remove the air line to the module, if there is oil in it you must flush the line, replace the air dryer filter and replace the AHD module air regulator valve (mounted behind the air dryer). Failing to do so will cause the AHD module to fail prematurely. 

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Okay, I replaced the whole module along with new sensors.  Is there a process to bleed the lines?  Also, will the fault code clear by itself?  Thank you for the help by the way, it is much appreciated!

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Figured it out and fault code went away.

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On 11/17/2017 at 10:51 PM, turckster said:

I've been replacing a lot of the AHD (aftertreatment hydrocarbon doser) modules lately because of oil contamination in the air line to the module. The oil contamination causes the shut off valve inside the AHD module to fail. Remove the air line to the module, if there is oil in it you must flush the line, replace the air dryer filter and replace the AHD module air regulator valve (mounted behind the air dryer). Failing to do so will cause the AHD module to fail prematurely. 

 

THis should be on your priority list!

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I have the same issue can y’all tell me where it is locator the ahi module I have the same mp8 I can’t find it


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2 hours ago, terantrucking93 said:

I have the same issue can y’all tell me where it is locator the ahi module I have the same mp8 I can’t find it


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It's located below, and in between the ecu and the air compressor. 

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It's located below, and in between the ecu and the air compressor. 


I have one more question my lines for my a/c they freezing up I blow my condensor it’s clean from the outside I know it has a filter but any body can get me a location


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On 5/15/2019 at 11:30 PM, terantrucking93 said:

 


I have one more question my lines for my a/c they freezing up I blow my condensor it’s clean from the outside I know it has a filter but any body can get me a location


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Filter should be right next to the evap, behind the center panel. Is your ac compressor cycling? If not could be a bad thermostat. Also make sure it has the correct charge amount.

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