SPN 4374 FMI 14 code on a 2017 Cascadia with DD15

Hello everyone, wondering if anyone has gotten this code or has an idea what it can be? SPN 4374 FMI 14. I have a 2017 Cascadia DD15 with 600k miles

 

9 times out of 10 it is a failed DEF pump. Before you replace remove and inspect/replace DEF pump filter.

 

Should I change the lines as well if it is the Pump?

 

Here's the diagnostic steps for the fault.

 

Before you condemn the pump, check the pressure at the doser with a manual gauge. The pressure sensor is in the doser, and I've seen a truck where techs changed the pump twice, only to find out the sensor in the doser failed.

 

Mechanic so far said there is an Air leak causing this , he wanted to fix that before changing a pump

 

Mine is leaking from the fitting where it connects to the def pump. I found a small clamp on this fitting is broken and loosing def pressure. Code I got is SPN 4374 FMI 14. My question is Can I just replace small plastic clamp on this fitting to stop the leak or do I have to replace the hole heater line?
Any suggestion will be greatly appreciated.

 

Unfortunately you need to replace the heater line.