If you have a Paccar powered truck that is 2011+, then you need to be aware of your emission system. Learning about this system will ensure you are prepared before a breakdown occurs.

Paccar emissions are complicated. The reason we say this is because there are two aftertreatment ECUs for Paccars. One is used to control the DEF system and the other one is used to control the DPF system and keep the aftertreatment in sync with the engine ECU.

There are many different components that make up the DPF & DEF system. So it is best to understand the limitations so you are not stranded over the road. 

If you have a Volvo D13 then read about what to do when stuck in a 5 MPH derate in this blog post. 

5 MPH DEF derate explainer:

If you have an emissions-related issue, then you are going to enter the dreaded 5 MPH derate that gets enabled by the ECU.

The 5 MPH derate can happen at any time because if you lose connection or have a sensor problem, the truck will put you into derate very quickly.

How do you remove the 5mph derate?

This process can be done with only a few high-level tools, such as the dealer level Davie4 software by Paccar. Doing this service at the dealer is costly because you need to have your truck towed into the nearest dealer.

But remember, don’t let the mom & pop service shops fool you, ask them if they have the Davie4 or the capability to remove the 5 MPH DEF derate with a dealer level tool.

OTR Performance has developed a 5MPH DEF derate diagnostic and reset tool. OTR Diagnostics will reset the 5mph derate at the dealer level. OTR Diagnostics will give you the capability to perform these extensive resets yourself at a much lower cost.

Learn more about OTR Diagnostics here 


  1. OTR Diagnostics will reset the fault codes at the dealer level. This means that you can replace failed parts and/or check if the fault code is a “Ghost code”. You can reset the CEL and see if it comes back. Most of the time it won’t come back unless it’s an ongoing issue with that part and you need to have that system checked or replaced.
  1. OTR Diagnostics will reset the 5 MPH DEF derate. They send the reset at the highest dealer level to make sure you won’t need to visit a repair shop or dealer – saving you both time and money

Don’t find yourself stuck in the middle of your load having to trust someone else with your problems. Equip your truck with OTR Diagnostics today! #OwnYourJourney. 

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