03/18/2026
***BASIC DIAGNOSTICS YOU SHOULD KNOW REGARDING YOUR AFTERTREATMENT***
Basic diagnostics you should know
We are always getting asked the question why my engine wont perform an after-treatment regeneration…….????
A request usually follows to do a force regen. It is critically important to know that if your engine will not regen, a defect must be identified and corrected. Before your red, check-engine light appears and your engine derates, your onboard computers have attempted many program routines to help clean the DPF.
Your engine passively attempts to keep the DPF clean as your travel down the highway. If the DPF is not successfully cleaned, your yellow DPF light will illuminate, requiring the driver to help with the process.
At this point you have two options:
Change the mode in which the vehicle is being operated in order to get more heat into the exhaust, or stop and perform and active regen. If not, the red light will eventually illuminate, and then will shut down and derate. Of course, the best course of action is to do everything in your control to prevent this warning light from ever being activated.
Maintenance Checks
DPF problem prevention starts with basic maintenance. For example, if your fuel filter is extremely dirty, the engine may not be able to generate enough heat to regen itself or even allow you to initiate an active regen.
If this is not done when recommended, your engine performance could be negatively impacted, creating a condition that prevents sufficient heat for regeneration.
Your air filter may simply be so dirty that it restricts the amount of air required for the engine to reach top performance. Also, the DPF doser, an injector located in the exhaust after the turbo, can become clogged and should be cleaned periodically. If the truck will not enter a regen cycle, the DPF doser should certainly be evaluated.
One more area of concern, be sure that the DPF system is properly sealed. Leaks can be identified by the black soot residue near sealing surfaces.
The diagnostic checks referenced are not all-inclusive, but rather provide an initial guide to identifying why your DPF system will not begin a regeneration event.
At Air Flow Solutions, Inc. DPF and DOC cleaning are provided in the Dallas, Ft. Worth TX and surrounding areas. We perform DPF diagnostics and cleaning service in shop or in the field.
Contact us for any of you DPF & DOC needs or questions.
Billy
214-850-6185