American Truck & Trailer Repair Inc.

Diesel Diagnostics in Stockton, CA

American Truck & Trailer Repair provides heavy-duty diesel diagnostics in Stockton, California for semi-trucks and commercial diesel vehicles. Our technicians troubleshoot check-engine lights, fault codes, electrical problems, engine-performance issues, and aftertreatment faults at our Stockton facility and through mobile service when available.

Call (209) 663-6000Request Service

What We Diagnose

Accurate heavy-duty diesel diagnostics in Stockton — we find the root cause instead of guessing.

  • Check-engine lights and stored/active fault codes
  • Engine-performance issues — low power, poor economy, derates
  • Aftertreatment faults — DPF, EGR, DEF/SCR, regen problems
  • Electrical faults — no-start, charging, sensors, shorts
  • ABS, brake, and drivetrain warning lights
  • Intermittent problems that other shops couldn't pin down

Trucks & Engines We Work On

  • Freightliner, Peterbilt, Kenworth, Volvo, Mack, International, Western Star
  • Detroit DD13 / DD15 / DD16
  • Cummins ISX / X15
  • PACCAR MX-13
  • Volvo D13

Our Diagnostic Process

  • 1We connect heavy-duty scan tools and pull active and stored codes.
  • 2We test the actual circuit or system — not just read the code.
  • 3We identify the root cause and explain it in plain language.
  • 4You get a clear estimate before any repair begins.
  • 5We verify the fix so the problem doesn't come back.

Diagnostics vs. Repair

A code is a starting point, not an answer. Clearing a light without fixing the underlying problem just brings it back — often with a derate at the worst time. Our diagnostics pinpoint the real fault so any repair we quote actually solves it. Once you approve the estimate, our technicians handle the repair in-house.

Frequently Asked Questions

My check-engine or DEF light is on — can you diagnose it?
Yes. We pull and interpret fault codes with heavy-duty scan tools, then verify the root cause rather than just clearing the code. That saves you from repeat failures and derates.
Can you diagnose intermittent electrical problems?
Yes — no-starts, charging issues, sensor faults, and wiring shorts are a core part of what we do. We trace the circuit to find the actual fault instead of swapping parts.
Which engines can you scan?
Detroit DD13/15/16, Cummins ISX/X15, PACCAR MX-13, Volvo D13 and other major heavy-duty diesel engines.

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 Diagnostics