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2021 Chevrolet Suburban
Reliability tier: verified - see /disclosure/
Engine: 3.0L Duramax LM2 (Duramax, 3.0L)
LM2 3.0L Duramax I6 (DOHC): 277 hp @3,750 / 460 lb-ft @1,500; aluminum block/head, Opel-derived I6 engineered in Turin, built at Flint; Hydra-Matic 10L80 10-speed. In-tank lift pump feeds the high-pressure pump.
Applicable failure modes (8)
- Coolant flow control valve failure (active thermal management)
- DEF system faults: tank heater, pump/quality (speed-limited derate)
- DPF regeneration and ash-loading faults
- EGR system failures: valve, cooler, wiring (derate-prone)
- Extended crank / long-crank no-start (air intrusion, check valve, cam wheel)
- NOx sensor / SCR efficiency codes
- Transmission control valve failure and rear-wheel lock-up (recall 24V-797)
- Turbo and boost-path faults (coolant line, charge air)
Applicable parts (13)
- 3.0L Duramax Engine Coolant Flow Control Valve (GM 24001355)
- DEF refill - fresh API-certified fluid (service item, all 3.0L Duramax)
- 3.0L Duramax DEF Tank Assembly, SUVs 2021-2023 (GM 86772598)
- DPF cleaning service (professional bake-and-blow, off-truck)
- 3.0L Duramax DPF Differential-Pressure Pipe (GM 55496942)
- 3.0L Duramax EGR Cooler (GM 55513487)
- 3.0L Duramax EGR Valve, high-pressure circuit (GM 55510043)
- 3.0L Duramax EGR Valve, low-pressure circuit (GM 55510254)
- 3.0L Duramax Fuel Filter / Water Separator Assembly (GM 13543066)
- 3.0L Duramax Fuel Filter Kit (GM 13539108)
- 3.0L Duramax Drop-In Fuel System / Lift Pump (FASS, 2019-2026 GM 3.0 LM2/LZ0)
- 3.0L Duramax Turbocharger (GM 40009138)
- 3.0L Duramax Turbo Wastegate Actuator Kit (GM 12716475)
Platform recipes (4)
- Coolant flow control valve job for the 3.0L Duramax (mode fm-lm2-coolant-control-valve): high fan, fluctuating temp, P1098, 'Engine Power Reduced'
- DEF tank-side service for the 3.0L Duramax (mode fm-lm2-def-system): the 'Exhaust Fluid System' warnings walk up a derate ladder to 5 mph
- EGR cooler / valve job for the 3.0L Duramax (mode fm-lm2-egr-system): rarely named in NHTSA complaints (8 of 1,190) but forum-documented - recurring 'Service Emission System' with the 65-mph derate
- Fuel filter service with a proper prime for the 3.0L Duramax (mode fm-lm2-long-crank): the #1 self-inflicted long-crank is air trapped after a filter change - seat the housing fully, cycle key-on and let the pump prime before cranking