Chapter 06 · Repair guides

DPF and DEF basics: avoiding aftertreatment headaches

Updated October 2026

Diesel particulate filters (DPF) and diesel exhaust fluid (DEF) systems keep modern trucks clean, and they can be expensive when they fail.

Good habits

Use quality DEF and keep it clean, let regenerations finish, don't ignore warning lights, fix boost and injector problems early, and follow the cleaning schedule for your DPF.

When warning lights come on

Get the codes read promptly. Some problems can derate the engine and leave you stranded.

Need a repair?

Tell us what's wrong and where you are. We'll pass your request to shops in our directory near you.

Your namePhone

EmailWhere's the truck?

City or nearest exitYear, make and model

What do you need?How soon?

Describe the problem

More guides

For your truck

Roadside Masters24/7 nationwide roadside assistance for trucks: towing, tires, jump starts and more.Sign up your truck Ad

Truck Parking ClubReserve safe parking while your truck is in the shop.Find parking Ad

Bluewhale InsurancePhysical damage and breakdown coverage quotes.Get a quote

Your next step

Does your policy cover breakdowns?Check physical damage and breakdown coverage.Check coverage Keep earning while it's in the shopRent a truck by the day or week.Find a rental