American Truck & Trailer Repair Inc.

DPF, SCR & Aftertreatment Repair in Stockton, CA

American Truck & Trailer Repair diagnoses and repairs diesel aftertreatment systems in Stockton, California — DPF, SCR/DEF, EGR, and regen problems that derate or shut down heavy-duty trucks. We clear faults and fix the root cause to get you back earning.

Call (209) 663-6000Request Service

What We Do

Diesel aftertreatment repair in Stockton — DPF, SCR/DEF, EGR, and regen problems that derate or shut down heavy-duty trucks.

  • DPF diagnosis, cleaning service, and replacement
  • SCR/DEF system — dosing, injectors, and pumps
  • EGR valves, coolers, and related faults
  • NOx, temperature, and pressure sensor diagnostics
  • Regen failures and forced-regen issues
  • Derate diagnosis and root-cause repair

Common Problems We See

  • Check-engine and DEF lights with active derates
  • Failed, frequent, or incomplete regens
  • DPF clogging and back-pressure faults
  • DEF-quality and dosing errors
  • EGR-related loss of power or overheating

Trucks & Engines We Work On

  • Detroit DD13 / DD15 / DD16
  • Cummins ISX / X15
  • PACCAR MX-13
  • Volvo D13

Fix the Cause, Not Just the Code

Clearing an aftertreatment code without fixing the underlying problem just brings the derate back — usually at the worst possible time. We diagnose the real cause and repair it so your truck stays out of derate and keeps earning. Call (209) 663-6000.

Frequently Asked Questions

My truck is in a derate — can you help?
Yes. Derates are usually triggered by aftertreatment or emissions faults. We diagnose the cause — DPF, SCR/DEF, EGR, or sensors — and repair it so the truck comes out of derate for good.
Do you fix regen problems?
Yes. Failed or frequent regens, DPF warning lights, and blocked filters are common issues we diagnose and repair.
What causes DEF/SCR faults?
Bad DEF quality, dosing and injector problems, NOx and temperature sensor faults, and wiring issues. We test the system to find which one is causing your code.

Get Your Truck Back on the Road

Call American Truck & Trailer Repair Inc. in Stockton, CA for fast, reliable heavy-duty service.

Call (209) 663-6000Request Aftertreatment Service