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ClaytonH729, Mechanic
Category: Medium and Heavy Trucks
Satisfied Customers: 755
Experience:  Expert in Freightliner trucks, From the Engine, to the taillights. Hit me with the most complex electrical problem also
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We have a 2009 Freightliner tractor with a Detroit 60series,

Customer Question

We have a 2009 Freightliner tractor with a Detroit 60series, this truck came in with a code for high soot level for the DPF unit. We sent out the DPF filter to get cleaned out and performed a forced regen with the laptop. The RPM's rev up but the DPF temperature never comes up higher than 330 degrees I believe the target range is at least 900 degrees, also the code for high soot level is active and wont let me erase it. My question is what would stop the DPF system from reaching its target temp and why cant I erase the code.
Submitted: 5 years ago.
Category: Medium and Heavy Trucks
Expert:  go-west.. replied 5 years ago.
can i get the actual code you getting please?
Customer: replied 5 years ago.
code 3719 Soot level very high
Customer: replied 5 years ago.
Relist: Other.
I still have not received an aswer.
Expert:  ClaytonH729 replied 5 years ago.

Hi, Welcome to Just Answer, I can help you with this.


Were there any INACTIVE codes with this ACTIVE code. Reason why I am asking is because the inactive codes can tell us why its not regening properly.


If the Inlet temps are not coming up, there are a few reasons.


The intake throttle valve closes so that the engine can heat up the exhaust enough to start the regen. If it does not close, it will not heat up.


You could have exhaust leaks in front of the Aftertreatment device.


The doser injector nozzle could be plugged up, or there is low fuel pressure to the nozzle.


Usually when I see this problem, you will get a Doser fuel supply pressure low or HIGH fault code INACTIVE in the list. Plugged fuel filters are the primary cause of this.


If the engine does not heat up due to bad thermostats, it will abort the regen also.



ClaytonH729, Mechanic
Satisfied Customers: 755
Experience: Expert in Freightliner trucks, From the Engine, to the taillights. Hit me with the most complex electrical problem also
ClaytonH729 and 3 other Medium and Heavy Trucks Specialists are ready to help you
Customer: replied 5 years ago.
There are no other codes along with the high soot level code, what do you recommend I try first in order to issolate the problem?
Expert:  ClaytonH729 replied 5 years ago.
If the only fault codes are the high soot level, and you cannot find anything wrong, you want to have auto elevate enabled if you idle a lot. Now about your problem, I would check for exhaust leaks, clamps on the after treatment device can leak if they are loose. If everything is fine, and the engine temps are around 180 to 200, check fuel pressure. Should be 78 psi to 86 psi. Remove the fuel temp sensor under the fuel pump, screw in a pressure guage here. Check pressure at idle, and check it at max rpm. Check the intake throttle valve, when you turn on the key, you should see it sweep0
Expert:  ClaytonH729 replied 5 years ago.
The intake throttle valves are junk, they fail all the time, even right out of the box. You might want to replace the doser injectors nozzle, or the fuel doser block.

I. would have regen ran with a laptop and watch the intake throttle valve operation, and fuel pressures during dozing.
Customer: replied 5 years ago.
We just noticed that the throttle valve and doser are working at the begining of the regen, but both cut out when the coolant temp falls below 135. is the coolant temp suppose to get this low during the regen?
Expert:  ClaytonH729 replied 5 years ago.
If the coolant temp doesn't get high enough, it will kick it out. It needs to get to 180 or the regen will abort.