Mobile Commercial Truck Diagnostics — Fremont & Bay Area
Check engine lights, warning lights, performance problems and electrical issues — diagnosed properly at your truck before any parts are replaced.
Proper diagnosis should happen before replacing parts
A fault code tells you which system reported a problem — not necessarily which part failed. A wiring fault can look like a bad sensor. A leak can look like a failed component. Replacing the most obvious part without testing is how truck owners end up paying twice.
Our approach is simple: understand the symptoms, read the codes and live data, test the suspected components and circuits, then explain what we found and give you an estimate. You decide what happens next.
What we diagnose
Check engine light diagnostics
Reading stored and active fault codes, then testing the system that set them to find the actual cause.
Warning light diagnostics
Stop engine, DPF, DEF, high exhaust temperature, charging and other dash warnings.
Electronic diagnostics
Using diagnostic software and live data to see what the truck's control modules are reporting.
Engine performance issues
Loss of power, derates, rough running, smoke, and poor fuel economy.
Starting problems
Hard starts and no-starts traced through the battery, starting, fuel and control systems.
Electrical problems
Dead batteries, charging problems, intermittent gauges, lights and wiring faults.
Commercial truck troubleshooting
Intermittent and hard-to-pin-down problems that need methodical testing.
How a diagnostic visit works
Tell us the symptoms
When it happens, how often, under load, cold or hot. Photos of warning lights help — you can upload them when booking.
We come to the truck
We drive to where it's parked, connect diagnostic equipment and read codes and live data.
Testing
We test the suspected components and circuits to confirm the cause.
Findings and estimate
We explain the problem in plain language and give you a repair estimate.
Your call
Approve the repair and we get to work — or take the findings with you.
Diagnostics after a Clean Truck Check
If your truck has a problem during Clean Truck Check testing, diagnostics is the next step. Because the same mobile team does testing and diagnostics, we can often start right away — no starting over somewhere else.
When should you get diagnostics?
Any warning light that stays on or keeps returning, loss of power, hard starting, electrical glitches, or a sudden drop in fuel economy. Read when to get truck diagnostics and our guide to common diesel truck warning lights.
Safety first: red warning lights, low oil pressure, overheating or a derate mean stop safely and call us — we're mobile and open 24 hours, so the truck doesn't have to be driven anywhere.
Diagnostics FAQ
What happens if my truck has a problem during testing?
We'll explain what the test found in plain language. Many issues show up as stored fault codes or emissions-related readings. From there, you can have us diagnose the cause and give you a repair estimate. Nothing is repaired without your approval.
Can you diagnose my truck after the test?
Yes. We're a full-service mobile truck mechanic, not just a tester. If testing points to a problem, we can move straight into diagnostics on the spot instead of sending you somewhere else.
Why should I pay for diagnostics instead of just replacing the part?
Because the part that seems obvious isn't always the cause. Warning lights and symptoms can have several possible sources. A proper diagnosis finds the real problem, so you don't pay for parts you didn't need and the truck doesn't come back with the same issue.
My check engine light is on. Is it safe to keep driving?
It depends on the problem and on which lights are on. A flashing light, a red stop light, a derate, low oil pressure or overheating warnings mean you should stop safely and call for help. For a steady amber light, get it checked soon — small problems tend to get more expensive when ignored.
Can I send photos of my warning lights before you come?
Yes. When you book diagnostics or repair online, you can upload photos of your dashboard or the problem area. It helps us bring the right tools and parts.
Will I get an estimate before repairs begin?
Yes. We diagnose first, explain what we found, and give you an estimate. No repair work starts without your approval.
How much do diagnostics and repairs cost?
It depends on the problem and the truck. We'll confirm diagnostic pricing before we start, and after diagnosis you get an estimate for the repair. You approve costs before work goes ahead.
After diagnosis
Truck Repair
Mobile mechanical and electrical repair for commercial trucks, quoted after diagnosis so you know the cost before work starts.
Quoted after diagnosis
Preventive Maintenance
Scheduled maintenance for owner-operators and small fleets — oil, filters, fluids and inspections planned around your routes.
Priced by maintenance plan
CARB Clean Truck Check
Mobile Clean Truck Check (CTC) testing for trucks, buses and motorhomes — any vehicle that needs it — by a CARB-credentialed tester, with diagnostics and repair if there's a problem.
$79
Helpful guides
Schedule truck diagnostics
Upload a photo of your warning lights when you book.