Cummins 6.7L Diesel Repair in Louisville | Turbo, Injectors & Emissions Specialists
Fuel systems, turbo, DPF, emissions, CP4 pump, VGT actuator, and EGR diagnostics for your Cummins 6.7L.
Signs Your Cummins Needs Repair
Schedule a diagnostic if your truck has:
| Symptom | What It Could Mean |
|---|---|
| Hard start, long crank, or no-start | CP4 pump failure, fuel system air, injector leak, or sensor issue |
| White smoke / black smoke | Injector leak, overfueling, turbo underboost, or DPF restriction |
| Loss of power under load | Turbo actuator failure, boost leak, or fuel pressure drop |
| Check engine light on | Stored codes that need scanning and live data analysis |
| DPF regen cycles too frequent | Clogged DPF, bad EGR valve, failed DOC, or oil level too high |
| Fuel in oil / misfire | Injector failure, CP4 debris, injector seal failure, or harness chafing |
| Turbo whine or whistle | VGT actuator failure, worn turbo bearings, or boost leak |
Our Diagnostic Process
Every Cummins follows a diagnostic-first workflow:
- Code Scan & Freeze Frame — Stored codes, pending codes, and fault conditions.
- Live Data Analysis — Fuel rail pressure, turbo boost, injector pulse width, EGTs, DPF pressure differential, and fuel trims.
- Visual & Mechanical Inspection — Wiring, connectors, oil contamination, coolant condition, and air restriction.
- Component Testing — Injector return flow, compression, turbo actuator calibration, and fuel pressure validation.
- Root Cause Report — Written findings, repair recommendation, and cost before parts replacement.
Fuel Systems & Injectors
Fuel system failures get expensive when CP4 debris spreads through injectors, rails, lines, and return components.
CP4 Pump Failure: The CP4.2 high-pressure fuel pump (2010-2018 Ram 6.7L) can cause hard start, white smoke, P0087, P0088, P1093, metal shavings in the fuel filter, or engine stall while driving.
What we do: Full fuel system inspection, CP4 replacement with CP4 or CP3 conversion kit, fuel system flush, and injector replacement if contaminated. We inspect the full system — not just the pump.
CP3 Conversion: For 2013-2018 Ram 6.7L trucks, we offer CP3 conversion using the pre-2010 Cummins pump design. This eliminates CP4 failure risk permanently.
VP44 Injection Pump (5.9L Cummins): The VP44 (1998-2002 5.9L 24-valve) often fails when lift pump supply is weak. We perform VP44 replacement, lift pump upgrade (FASS or AirDog recommended), and injector return flow testing.
Fuel Injector Service: Worn injectors can cause white smoke, rough idle, misfire, poor fuel economy, and oil dilution. We perform injector testing, replacement, fuel rail pressure sensor replacement, and injection pump calibration when applicable.
Turbocharger Service
The Cummins 6.7L uses a VGT turbo with an electronic actuator. We test actuator control, boost pressure, shaft play, and turbo condition before repair.
VGT Actuator Failure: Symptoms include loss of power, limp mode, low boost, and P003A, P0046, P0299, or P2262 codes. We handle actuator calibration, actuator replacement, turbo rebuild, or complete turbo replacement.
Turbo Replacement / Rebuild: If bearings, compressor wheel, shaft play, or housing damage confirm failure, we install OEM or high-quality aftermarket units. We do NOT install cheap turbos that will fail in 20,000 miles. Some turbos can be rebuilt with bearings, seals, and a rebuilt actuator.
DPF, DEF & Emissions
We diagnose DPF, DEF, EGR, NOx, and DOC faults before replacing emissions parts.
DPF (Diesel Particulate Filter): We perform pressure differential testing, forced regeneration when safe, DPF cleaning (thermal or chemical), and DPF replacement only when cleaning will not work.
DEF (Diesel Exhaust Fluid) System: We service DEF injector nozzles, DEF heaters, NOx sensors, and DEF pumps. NOx sensors are verified before replacement because they are often misdiagnosed.
EGR Valve: Soot buildup can cause rough idle, check engine light, reduced power, and excessive regen cycles. We perform EGR cleaning, replacement, and EGR cooler inspection.
⚠️ Off-Road Delete Tuning: We offer DPF/EGR/DEF delete tuning for off-road and competition vehicles only. All delete work is clearly labeled for off-road use. We do NOT offer delete tuning for on-road vehicles. If you need on-road emissions repair, we can fix your existing system to factory specifications.
Sensors & No-Start Diagnostics
Sensor faults can cause derate, stall, poor performance, or no-start.
| Sensor | Failure Symptoms | Common Fix |
|---|---|---|
| Crankshaft Position Sensor (CPS) | No-start, stalls while driving | Replacement (common on 5.9L and early 6.7L) |
| Camshaft Position Sensor | No-start, engine dies | Replacement |
| Fuel Rail Pressure Sensor | Power loss, rough idle, P0087/P0088 | Diagnosis — could be sensor OR pump |
| MAP / Boost Sensor | Low power, black smoke, P0234/P0299 | Diagnosis — sensor or actual boost leak |
| EGT Sensors (x4) | Regen issues, derate, check engine | Replacement (frequent on 2013+) |
| NOx Sensors (x2) | Check engine light, derate | Diagnosis REQUIRED — often misdiagnosed |
A crank/no-start Cummins is tested in this order: rail fuel pressure (lift pump AND CP4/CP3), injector electrical signal, cam/crank sync, ECM communication, and compression.
Oil Change & Preventive Maintenance
Proper maintenance extends Cummins engine life:
- Full synthetic 5W-40 diesel oil change (the factory-recommended weight for 6.7L Cummins)
- Fuel filter replacement (both filters on 6.7L — this is critical and often skipped)
- Multi-point inspection (fluids, belts, hoses, brakes, suspension, DPF ash load)
- Air filter replacement
- Coolant flush (SCA-treated coolant for diesels)
- Transmission service (see our transmission diagnostics page for details)
Frequently Asked Questions
My check engine light is on but the truck runs fine. Can I keep driving?
It depends on the code. EGT sensor codes may not damage the engine immediately, but CP4 fuel pressure codes can leave you stranded. Scan the code before continuing to drive around Louisville.
Is the CP4 pump really that bad?
Yes. The CP4.2 is a known failure point on 2013-2018 Ram 6.7L trucks. Many owners convert to CP3 before failure.
How much is a CP4 replacement?
Contact us for current pricing. Cost depends on whether metal debris contaminated the injectors, rails, and lines. We inspect the full system before quoting.
Can you program my ECM for delete tuning?
For off-road and competition vehicles only, yes. We do NOT offer delete tuning for on-road vehicles.
My truck goes through regen every 100 miles. Is that normal?
No. Normal regen interval is 300-700 miles depending on driving conditions. Regen every 100 miles or less usually points to a DPF, EGR, or sensor problem.
Do you work on 5.9L Cummins too?
Yes. We service Cummins diesel engines, including 5.9L 12-valve, 5.9L 24-valve, and 6.7L ISB. Our tools cover multiple years and configurations.