Cummins 6.7 problems Chico CA. CP4 fuel pump, EGR cooler, DPF, DEF, EGR valve. Ram 2500/3500. Written diagnosis. (530) 826-4275.
The Cummins 6.7L in Ram 2500/3500 (2007.5–present) has several documented failure patterns. CP4.2 high-pressure fuel pump (2019+), EGR cooler failure, DPF/DEF/SCR faults, and EGR valve failure are the most common in Chico. Diagnosis before any repair recommendation.
The 6.7L Cummins replaced the 5.9L in 2007.5. It is a capable engine but with specific failure modes: CP4.2 fuel pump (2019+), EGR cooler failure, DPF/DEF/SCR system complexity, and EGR valve sticking. Each requires specific diagnosis before any repair is recommended. By Buddy Rausch, Owner / ASE Master Technician · Reviewed May 20, 2026
2019+ Ram 6.7L uses the Bosch CP4.2. Catastrophic failure sends metal debris through the entire high-pressure fuel system. Injectors, rails, and return lines all require replacement. Can exceed $10,000–$15,000. Prevention: fuel filter every 15,000 miles, no B20+ biodiesel, lubricity additive.
Internal cracking causes coolant to enter the exhaust — white smoke, sweet smell, coolant loss, overheating. Mimics head gasket failure. HC combustion test confirms before teardown. EGR cooler replacement resolves without head gasket work.
DPF regen failures on short-trip Chico trucks. DEF quality faults. NOx sensor failures causing limp mode. We diagnose the specific fault before recommending any emissions system replacement.
Sticks open or closed — rough idle, black smoke, power loss, P0404/P0406 codes. Carbon buildup on the pintle is most common — often cleaned rather than replaced. We test live data before recommending replacement.
6 plugs (one per cylinder). Hard cold starts and white smoke at startup indicate failure. Current clamp test identifies which plugs failed. Set replaced if 3+ show failure at same mileage.
Oil: 5,000–7,500 mi with 15W-40 CK-4 or 0W-40. Fuel filter: every 15,000 mi (critical for CP4.2). DEF: top off as needed. DPF monitoring at every service. From $169.99 oil change.
CP4.2 fuel pump failure (2019+), EGR cooler failure, DPF/DEF/SCR faults (NOx sensor, regen), EGR valve failure, and injector wear at high mileage.
Fuel filter every 15,000 miles, no biodiesel above B5, lubricity additive with Chico area diesel, and monitor for fuel pressure drop codes indicating early CP4 wear.
Most likely EGR cooler failure. Less likely: head gasket (rare on 6.7L) or external leak. HC combustion test and chemical block test confirm source before teardown.
Most common: NOx sensor failure, DPF soot overload, DEF quality fault, or EGR valve issue. We scan all module codes and live data to identify the specific fault.
Every 15,000 miles — no exceptions on 2019+ trucks with CP4.2. Water separator drained at every oil change. Neglecting the filter is the primary contributor to CP4.2 failures.
Written estimate before any work · NAPA Gold warranty · ASE Master Tech
📍 2695 CA-32, Chico, CA 95973 · Open Mon–Fri 7AM · Sat 8AM · Sun 9AM — Close 5PM · Open 7 Days
2695 CA-32, Chico · (530) 826-4275 · Cummins · Duramax · PowerStroke
Buddy Rausch founded Tedious Auto Repair in Chico, CA in 2007 and has been serving Butte County for 18+ years. As an ASE Master Technician, Buddy personally oversees diagnostics and quality control on every vehicle. All content on this page reflects real procedures, OEM specifications, and cases seen in the shop. About Buddy Rausch, ASE Master Tech →
Buddy Rausch founded Tedious Auto Repair in Chico, CA in 2007. ASE Master Certified. 18+ years serving Butte County. About Buddy Rausch