Diagnose it once. Fix it right.

Modern diesels throw fault codes that point toward a system, not a part. A P20EE "low SCR efficiency" code can be a bad NOx sensor, a leaking DEF doser, a clogged SCR substrate, a wiring fault, or a failed DEF pump. Five different repairs — five wildly different price tags.

We don't chase parts. Every diagnosis starts with a full ECM scan across every module on the bus, a live-data capture under load, and — where relevant — pressure testing, smoke testing, and scope work on the electrical side. We find the actual cause, document it, and walk you through it before anything gets replaced.

It's the reason fleets stay with us. Nobody wants to pay for the same fault twice.

From a single fault to a full overhaul, we handle diesel engine service and repair on heavy-duty trucks under one roof. The common jobs: diesel engine oil leak repair — front and rear main seals, valve-cover and oil-pan gaskets, oil coolers and lines — plus coolant leaks, blow-by, low power, rough idle, and hard starts.

We pressure-test and confirm the source before we open anything up, so an oil leak that looks like one thing isn’t misdiagnosed as another. We repair it with the right parts and verify the engine is dry before the truck leaves.

Looking for diesel engine repair service near you in the Inland Empire? We’re at 5433 G Street in Chino, serving Ontario, Fontana, Riverside, Jurupa Valley and the surrounding valley — Monday through Friday.