Cummins
The Cummins ISX15 and X15 are everywhere in this region, and we see the same handful of failure points again and again — EGR cooler cracking, NOx sensor failure, and cylinder liner fracture chief among them. We diagnose to the platform's actual known weaknesses, not a generic checklist.
- Displacement
- 15L (ISX15 / X15)
- Common in
- Freightliner, Peterbilt, Kenworth, International
Known failure signature
- EGR cooler cracking — the most common cause of white smoke and coolant loss on this platform
- NOx sensor failure — a frequent trigger for SCR efficiency codes and derates
- Camshaft and rocker wear from oil starvation — worth checking on high-mileage units
- Cylinder liner fracture — a serious failure mode we check for during any major engine work
- Fuel pump failure tied to the 2017 recall era, and fuel filters that clog more readily than other platforms
Services we perform on this platform
EGR Valve & Cooler Repair
White smoke at startup and coolant that disappears without a visible leak is the classic sign of a cracked EGR cooler letting coolant cross into the exhaust. We pressure-test the cooling system to confirm it before anything comes apart.
Learn more Emissions
Engine Derate Diagnosis & Repair
A derate means the ECM has decided the truck can't be trusted to run at full power — pull over safely, don't keep pushing it, and call. We read the fault code, trace it to sensors, DEF quality, or the aftertreatment system, and get you back to full power instead of just clearing the light.
Learn more Emissions
DEF & SCR System Repair
A DEF quality fault or an SCR efficiency code usually comes down to one of a handful of things — bad fluid, a failing sensor, a frozen line, or the catalyst itself losing efficiency after years of duty. We test each one separately instead of replacing parts until something clears.
Learn more Engines
Fuel System & Injector Repair
Hard starts, rough idle, and power loss often trace back to the fuel system before anything else — injectors, the high-pressure pump, or contaminated fuel. We test the system in order instead of replacing the most expensive part first.
Learn more Engines
Diesel Engine Repair
A diesel engine problem is rarely simple — it's cylinder head, fuel system, turbo, or something deeper, and the fix ranges from a single component to a full overhaul. We diagnose first, then tell you honestly whether it's worth repairing, overhauling, or replacing.
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Diagnostic tools we use
Common questions
What are the most common problems with the Cummins X15?
EGR cooler cracking, NOx sensor failure, and cylinder liner fracture are the ones we see most. Camshaft and rocker wear from oil starvation shows up on higher-mileage units.
Is the 2017 fuel pump recall still relevant?
It can be, on units from that era that haven't had the pump addressed. Worth checking service history if you're unsure.
What diagnostic tool do you use on Cummins engines?
Cummins INSITE primarily, plus JPRO for cross-platform diagnostics.
Do you do full overhauls on the X15?
Yes — in-frame and out-of-frame. See /services/engine-overhaul for how we decide which one fits.
Ready when you are
Call now or send a quote request — we’ll tell you what it takes to fix it.