Used 6.7 Cummins 2019+: what to check before you buy

1Before you go

Run the VIN and ask for the paperwork on the campaigns below: a done recall or program is a solved problem, an open one is a free repair the seller has not had done.

• Run the VIN

  It confirms the engine and lists the campaigns for that model year. Whether a recall is still open on this VIN: nhtsa.gov/recalls.

• Safety recalls on this engine
  • 23V-060 · 2021-2023 · Electrical system
  • 22V-642 · 2022 · Engine and engine cooling
  • 21V-880 · 2019-2020 · Fuel system, diesel
  • 21V-798 · 2021-2022 · Electrical system
  • 21V-439 · 2019-2020 · Engine and engine cooling
  • 21V-163 · 2021 · Electrical system
  • 20V-511 · 2019-2020 · Engine and engine cooling
  • 19V-498 · 2019 · Fuel system, diesel
• Programs, extended coverages and emissions recalls
  • Emissions Recall Y43 · Emissions recall · 2021-2022 Ram 3500, 4500, 5500 (owners of 2022 Ram 2500 also report it)
  • Warranty Extension X97 (09-014-22) · Special coverage / warranty extension · 2021-2022 Ram 3500 and 4500

  Plus 2 service bulletins on the recalls page.

2Cold start and idle

Ask the seller not to start or warm the engine before you arrive. Most of these only show on a cold engine; then let it idle and listen.

• CP4 high-pressure fuel pump failure and fuel system contamination (2019-2020 6.7)
  • sudden loss of power and stall, often with no warning or after a 'Service Exhaust System' type message; may not restart
  • codes P0087 (rail pressure too low), P008A (low-pressure side too low), P0201-P0206 (injector circuits); engine will not start
• Grid heater bolt and relay failures (2019+ 6.7)
  • code P2609 (intake air heater circuit) and P0542; long crank and white smoke in cold weather
• Common-rail injector wear (2019+ 6.7)
  • cold-start rattle and white smoke; uneven idle; rising fuel consumption
• EGR cooler failure (2019+ 6.7)
  • coolant drop with no external leak; white smoke on cold start

3Scan for codes

A basic OBD-II reader shows stored and pending codes; on a diesel ask a shop for a full scan if you can. These are the codes our records tie to known failures on this engine.

What a code means on each engine: trouble codes by engine.

4Hood up and underneath

Engine off, in daylight, with a flashlight.

• CP4 high-pressure fuel pump failure and fuel system contamination (2019-2020 6.7)
  • metal debris in the fuel filters once the pump has come apart

  To confirm: check the VIN for recall 21V-880 / Y78 first

5Test drive

At least 20 minutes, including a highway run and a hill or a load if you can.

• DPF/SCR aftertreatment problems (2019+ 6.7)
  • 'exhaust filter full' / regen messages; DEF quality warnings; speed-limiting derates
  • failed regens on short trips; NOx sensor faults
• Grid heater bolt and relay failures (2019+ 6.7)
  • knocking at speed after the heater's terminal nut or bolt breaks off and is pulled into a cylinder (owners most often name cylinder 6)
• VGT turbo electronic actuator failure (HE300VG family)
  • underboost/overboost DTCs and defuel; lazy spool; soot build-up from stuck vanes
• DEF quality / freezing inducements (2019+ 6.7)
  • 'DEF quality low' warnings and countdown to speed limit
  • hard derates after cheap/contaminated DEF or a failed DEF heater in freezing weather

6After the drive

Hot engine, parked: the dipstick and the coolant reservoir tell you what the drive did. Then shut it off and restart it hot: some failures only show on a hot restart.

• Head gasket failure on tuned 2019+ 6.7
  • coolant push-out under boost, combustion bubbles in the degas bottle

  To confirm: combustion-leak test at the degas neck; log boost spikes

• In-tank lift pump failures (2019+ 6.7)
  • fuel pressure sag under load on a gauge; hard hot starts; injector rattle from starvation

  To confirm: fuel pressure gauge at the CP3 inlet - log hot and under load

What it costs if you find it

Parts budgets from our repair recipes for this engine: Dave's Auto Center's prices where Dave's lists the part, approximate OEM and maker catalog prices (rounded) for the rest; labor not included. A campaign listed next to a failure may make the repair free on a covered truck: check it by VIN.