← All symptoms
Symptoms
Loss of power, limp mode or derate
What causes it depends on the engine. 67 documented failures on 21 engines list this among their signs. Pick your engine for the causes ranked, how to tell them apart and the usual fix.
7.3 Power Stroke (1994.5-2003)
2 known causes, most widespread: Turbo up-pipe / donut gasket leaks
6.0 Power Stroke (2003-2007)
3 known causes, most widespread: Marginal regulated fuel pressure (blue spring)
6.4 Power Stroke (2008-2010)
2 known causes, most widespread: Piston ring failure #7/#8 (regen fuel wash)
6.7 Power Stroke (2011-present)
5 known causes, most widespread: DEF / SCR / NOx sensor faults
3.0 Power Stroke (2018-2021)
1 known cause: CP4.2 high-pressure pump failure (contamination cascade)
5.9 Cummins (1994-2007)
4 known causes, most widespread: 12v overflow valve weak (hard start / low power)
6.7 Cummins 2007-2018
6 known causes, most widespread: DPF clogging / regeneration problems
6.7 Cummins 2019+
4 known causes, most widespread: CP4 high-pressure fuel pump failure and fuel system contamination (2019-2020 6.7)
Ram 1500 EcoDiesel (2014-2019)
1 known cause: Bosch CP4.2 high-pressure pump failure (recall 22V-406)
Duramax LB7-LMM (2001-2010)
1 known cause: VGT turbo vane carbon / actuator wear (LLY+)
Duramax LML (2011-2016)
4 known causes, most widespread: Bosch CP4.2 high-pressure pump failure and fuel-system contamination
Duramax L5P (2017-present)
4 known causes, most widespread: DEF system failures: tank heater, dosing, quality (L5P)
Duramax 3.0 (LM2/LZ0)
7 known causes, most widespread: Coolant flow control valve failure (active thermal management)
3.2 Power Stroke (Transit)
3 known causes, most widespread: DPF / DEF-SCR aftertreatment messages and service ('Drive To Clean')
ProMaster EcoDiesel (2014-2016)
3 known causes, most widespread: DEF/SCR and DPF regen duty (2014-2016)
Sprinter 3.0 V6 (OM642)
4 known causes, most widespread: BlueTEC DEF/SCR: sensors, DEF quality, countdown derate (2010+)
Sprinter 2.1 (OM651)
4 known causes, most widespread: BlueTEC DEF/SCR service (2014-2018)
Triton (gas)
1 known cause: FPDM (fuel pump driver module) corrosion / failure
3.5 EcoBoost (gas)
5 known causes, most widespread: Charge-air-cooler condensation: boost shudder / hesitation in humid weather
Transit V6 (gas)
1 known cause: Fuel delivery: in-tank pump and injectors
ProMaster 3.6 (gas)
2 known causes, most widespread: 'Pentastar tick': rocker arms, hydraulic lash adjusters, cam damage
Built from the failure-mode records on this site: a failure is listed when its own symptom list describes this sign. Engines not shown have no documented failure with it in our records. How we tier and source facts.