Duramax Diesel Repair in Austin, TX
Silverado and Sierra 2500HD and 3500HD trucks — from LB7 injector jobs to L5P emissions work, diagnosed properly and repaired to last.
Duramax service at an independent Austin shop
Duramax generations are different enough that guessing gets expensive: an LB7 injector job and an LML fuel-system failure share symptoms but almost nothing else. We identify the engine, test what that generation actually loses, and quote from findings.
Duramax generations we service
- LB7 (2001–2004) — Injectors under the valve covers — a known job, and one worth doing once, correctly.
- LLY / LBZ / LMM (2004–2010) — Overheating on the LLY, head gaskets, and early DPF emissions work on the LMM.
- LML (2011–2016) — CP4 fuel pumps, DEF system faults, and emissions-related derates.
- L5P (2017–present) — Emissions and DEF systems, sensors, and diagnostics on the current platform.
What we see fail on Duramax
- Injector failure and hard starting — Long crank, rough running, and fuel-return imbalance — the LB7 signature, and not only the LB7.
- CP4 fuel pump failure — On LML trucks, a failed CP4 sends metal downstream. Doing it halfway means doing it twice.
- Overheating and head gaskets — LLY-era cooling problems that turn into head gasket damage if they are ignored.
- DEF and emissions faults — DEF quality and injector faults, DPF loading, and the countdown derates that follow.
- Turbo vane sticking — Soot-bound vanes causing low boost and a truck that feels flat under load.
Duramax work we handle
- Generation-specific diagnostics with live scan data
- Injector replacement and fuel-system service
- CP4 and high-pressure pump work, including full system cleanup
- Cooling-system repair, head gaskets, and engine work
- DPF cleaning, DEF system repair, and emissions diagnostics
- Turbocharger service and replacement
Modern Diesel is an independent, Christian, veteran-owned shop — we service Duramax engines but are not a dealer or affiliated with the manufacturer. Warranty coverage on our work is set with your service advisor at the time of service.
Related services
Other diesel platforms we service
Power Stroke · Cummins · Mercedes-Benz diesel · Detroit Diesel
Bring it to the shop
We work on Duramax at our shop at 2900 N FM 973, Austin, TX 78725, serving the Greater Austin Area (Travis, Bastrop, Williamson, Hays) — Austin, Del Valle, Manor, Elgin, Pflugerville, Round Rock, and the surrounding counties. Call 512-717-2777 and tell us what it's doing, or send us the details and we'll get back to you.
Common questions
Do you do LB7 injector jobs?
Yes. LB7 injectors sit under the valve covers, so it is a labor-heavy job worth doing once and doing right — we test fuel return to confirm the injectors are actually the problem before quoting it.
My LML lost its CP4 pump. Do I need the whole fuel system?
Usually more than just the pump. When a CP4 fails it sends metal downstream into the rails, lines, and injectors, and cleaning only part of the system is how people end up paying twice. We inspect the system and tell you exactly what is contaminated.
Can you turn off the emissions system on my Duramax?
No. Emissions defeat and delete work is illegal for a shop to perform on a road-going vehicle, and it makes a truck fail inspection. What we do instead is repair the emissions system properly so it stops causing derates.
Ready when you are.
Drop by the shop at 2900 N FM 973, Austin, TX 78725 or call and we’ll get you scheduled.