← Power loss / limp mode on all engines
Symptoms · 6.7 Cummins 2019+
6.7 Cummins 2019+: loss of power, limp mode or derate
4 documented failures on this engine list this among their signs. They are ordered from the most widespread down. Each one shows the signs in its record's own words, how to tell it from the others, the usual fix and any recall or bulletin.
Not sure which engine you have, or want the recalls for your exact truck? Check your VIN: it names the engine and lists the campaigns for that model year. Whether a recall is still open on your VIN: nhtsa.gov/recalls.
verified
How widespread: Very common
66 NHTSA owner complaints match it, out of 318 checked
How it shows up
- sudden loss of power and stall, often with no warning or after a 'Service Exhaust System' type message; may not restart
Its other signs
- codes P0087 (rail pressure too low), P008A (low-pressure side too low), P0201-P0206 (injector circuits); engine will not start
- metal debris in the fuel filters once the pump has come apart
How to tell it apart
- check the VIN for recall 21V-880 / Y78 first
- on a stall or no-start, inspect the fuel filters for metal before replacing parts
- a CP3.3 pump looks and sounds different from the CP4; bulletin 14-008-22 explains the identification differences
Usual fix
recall Y78: CP3.3-style pump, PCM update and fuel system parts as needed, free at a Ram dealer
Recalls and bulletins
21V-88018-099-22 / 18-054-2114-008-22
Root cause, parts and sources →
verified
How widespread: Common
27 NHTSA owner complaints match it, out of 318 checked
How it shows up
- 'exhaust filter full' / regen messages; DEF quality warnings; speed-limiting derates
Its other signs
- failed regens on short trips; NOx sensor faults
How to tell it apart
- read soot-load/DEF DTCs first; verify regen completes at highway load
- rule out VGT/EGR faults that block regen conditions
Usual fix
service the aftertreatment path: sensors, DEF quality, DPF cleaning/replacement as indicated
Recalls and bulletins
Emissions Recall Y43Warranty Extension X97 (09-014-22)
Root cause, parts and sources →
verified
How widespread: Common
How it shows up
- underboost/overboost DTCs and defuel; lazy spool; soot build-up from stuck vanes
Its other signs
- actuator learns/calibrates repeatedly then faults again
How to tell it apart
- log desired vs actual boost; exercise the vane position with a scan tool
- inspect the actuator linkage and vane lever for carbon; check for audio gear-grind at key-off calibration
Usual fix
replace/rebuild the electronic actuator; clean or replace the turbo if vanes are seized
Root cause, parts and sources →
verified
How widespread: Occasional
How it shows up
- 'DEF quality low' warnings and countdown to speed limit
- hard derates after cheap/contaminated DEF or a failed DEF heater in freezing weather
How to tell it apart
- read DEF quality/NOx DTCs; test DEF with a refractometer before replacing sensors
- verify DEF heater operation in freezing climates
Usual fix
drain and refill with fresh API-certified DEF; replace failed sensors/heaters as diagnosed
Root cause, parts and sources →
Other symptoms on the 6.7 Cummins 2019+
Hard start, long crank or no-startWhite smoke from the exhaustLosing coolantTicking, knocking, rattle or whineDEF, DPF and regeneration warnings
Everything on the 6.7 Cummins 2019+Its recalls and bulletins