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How Long Should a Forced DPF Regeneration Last? As Well as Other Tell-Tale Symptoms of a Successful (or Unsuccessful) Forced DPF Regeneration?

For the sake of this blog post let's just assume you have OTR Diagnostics. Let’s also assume that all of a sudden you have some downtime, which is perfect since you've been noticing that the truck has been giving you occasional warning signs.

So, you decide it’s a good idea to do a forced DPF regen to get ahead of the potential derates and forced (or parked) regen request that always happens at the absolute worst times possible.

You sit there while the truck goes on and on with the high idle, dash notifications, DPF lights lit, and like clockwork 45 minutes later the idle drops back to its normal burble. You step outside your truck and enjoy the sweet smell of success (or burnt soot if this is going as glorious as we imagine).

Just like most other operators that are using our tool for preventative maintenance, this would be the typical experience. Unfortunately, far too often it does not go quite as smoothly. 

3 Indicators of a successful forced DPF regen

First, as a general rule of thumb, a forced DPF regen should last approximately 45 minutes. There may be small variances, but in general, this is the amount of time it should take for the exhaust temperature to build up in all the components, for the 7th injector to start injecting diesel into the exhaust stream, and for the reaction of exhaust gas and diesel in the DOC to take place and burn the soot throughout the DPF.

Secondly, you'll also notice that there's a unique smell that emits from the tailpipe when the soot trapped in the DPF is burning off into ash.

And finally, you'll also be able to feel the temperature increase on the exhaust components from beginning to end. If you have an infrared thermometer you can even monitor exhaust temperatures during the forced DPF regen and you’ll see a clear change in temperature before the DOC + DPF, in the DOC + DPF, and after the DOC +DPF as the forced DPF regen process moves along.   

    What does it mean if your forced DPF regen lasts longer than normal?

    I imagine that as you were reading this short blog post you can recall a time when your truck may not have given you the three successful indicators. If your forced DPF regen lasts closer to an hour or continues beyond that, it likely suggests that your exhaust temperatures are not building up high enough to successfully burn off the soot collected in the DPF and that the truck is still trying to bring down those soot levels.

    In a future blog we will dive deeper into what causes a longer forced DPF regen. But keep this in mind: it requires your attention sooner rather than later.

    What does it mean if your forced DPF regen is shorter than normal?

    If a forced DPF regen drops out before a half hour it would typically indicate an issue was detected by the computer and that it needs to exit the regen process. The computer detected an issue with a vital component in the regen process and so it could not continue. 

    Typically, you’ll also get an associated trouble code that gives you a fairly clear picture of what is going on.

    We hope this blog post empowers you to make some mental notes that stay in the back of your mind to keep you spending more time on the road clicking off miles and less time dealing with unexpected repairs.

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

    Looking to learn more? Check out our other blog posts.

    OTR Diagnostics allows you to read and reset fault codes, view live data, and run advanced diagnostic functions, including forced DPF regen with your mobile phone or tablet. 

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