Dan107 Posted November 17, 2017 Share Posted November 17, 2017 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. Quote Link to comment Share on other sites More sharing options...
64C85 Posted November 17, 2017 Share Posted November 17, 2017 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. Quote Link to comment Share on other sites More sharing options...
Dan107 Posted November 17, 2017 Author Share Posted November 17, 2017 Thank you! I'll check it out today... Quote Link to comment Share on other sites More sharing options...
Dan107 Posted November 17, 2017 Author Share Posted November 17, 2017 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? Quote Link to comment Share on other sites More sharing options...
Dan107 Posted November 17, 2017 Author Share Posted November 17, 2017 Found it! Quote Link to comment Share on other sites More sharing options...
turckster Posted November 18, 2017 Share Posted November 18, 2017 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. Quote Link to comment Share on other sites More sharing options...
Dan107 Posted November 18, 2017 Author Share Posted November 18, 2017 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! Quote Link to comment Share on other sites More sharing options...
Dan107 Posted November 18, 2017 Author Share Posted November 18, 2017 Figured it out and fault code went away. Quote Link to comment Share on other sites More sharing options...
fjh Posted November 19, 2017 Share Posted November 19, 2017 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! Quote Link to comment Share on other sites More sharing options...
terantrucking93 Posted May 11, 2019 Share Posted May 11, 2019 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 itSent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
steeler Posted May 12, 2019 Share Posted May 12, 2019 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 Sent from my iPhone using Tapatalk It's located below, and in between the ecu and the air compressor. 1 Quote Link to comment Share on other sites More sharing options...
terantrucking93 Posted May 14, 2019 Share Posted May 14, 2019 Found it thank u Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
terantrucking93 Posted May 16, 2019 Share Posted May 16, 2019 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 Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
steeler Posted May 17, 2019 Share Posted May 17, 2019 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 Sent from my iPhone using Tapatalk 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. Quote Link to comment Share on other sites More sharing options...
terantrucking93 Posted May 22, 2019 Share Posted May 22, 2019 left side it is froze .my compressor it is doing the cycling Sent from my iPhone using Tapatalk Quote Link to comment Share on other sites More sharing options...
steeler Posted May 22, 2019 Share Posted May 22, 2019 How are the pressures? Quote Link to comment Share on other sites More sharing options...
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