Doser Valve Cleaning 

Essential Takeaways

  • The 7th injector is a common component that can be full of soot causing regen issues.
  • You have two options when it comes to cleaning your doser valve. You can either can get it cleaned at a dealership or repair facility, or you can do it yourself.
  • Cleaning the doser valve yourself can be relatively straightforward and cost-effective. You just need some basic hand tools and brass bristled brush.
  • With a cleaner doser valve, you will be operating at an optimal level.

One of the most common issues we see with aftertreatment systems is a failure to initiate or complete the regen process. It is not uncommon for the 7th injector (also known as the diesel doser) to become fouled up and clogged with soot over time. This situation is especially common for trucks that have been running rich (too much fuel); there will be an excessive amount of soot (unburnt fuel) going through the exhaust system and often creating carbon build up on your aftertreatment components.

So how is this corrected? You have two options.

First option: Go to a dealership or repair facility and have the work performed for you.

Second option:  Performing the work yourself and cleaning the 7th injector before moving forward on replacing parts.

The process is not impossible to tackle and requires only a few basic hand tools, a brass bristled brush and some patience.

To start you will remove the 7th injector, which should be relatively straightforward.

Remove any connections/lines and any hardware holding the 7th injector into the exhaust pipe. Now that you have the injector off you will likely see a fair amount of carbon soot build up on the end of the injector. You will need to use a brush to clean this buildup off the nozzle of the injector. If you have compressed air available, you can use it to help blow away any excess soot while you work your way through the brushing process.

For some applications, such as the DD15 engines, before reinstalling the injector you will want to run the wire brush (in a pinch a screwdriver will work) down into the injector port on the doser housing. The goal is to make sure that you have a clear path directly into the exhaust and no carbon build up blocking passage into the exhaust pipe. If you find that you have build-up or clogging in the housing, you will need to break through that to give the 7th injector a good path into the exhaust. Once that is all good to go you are ready for reassembly.

The reassembly process is the opposite of disassembly, in a perfect world you would have a replacement gasket (if your truck uses one), in a dire situation attempt to reuse your gasket. In that scenario plan to go back and replace it as soon as possible. Once everything is cleaned you can start reassembly.

Now that your injector is cleaned you should see less frequent regen requests from the truck as well the correct exhaust temps during regens. The exhaust temps being higher with a properly functioning doser will do a much better job burning off soot and keeping your system operating at its best performance. 

Until next time! 👋
Stay safe, stay healthy & be blessed.