Recipe - Duramax 6.6L V8 Turbo Diesel (GM HD, LML 2011-2016; LGH vans 2011-2016)
Specific Fix build
Reliability tier: verified - verify before ordering, see /disclosure/
DEF subsystem repair for the LML (mode DEF system failures: tank heater, dosing, quality (LML)) - the first DEF/SCR Duramax, and the early years carry the heaviest complaint load. Work the cheap electrics first (harnesses), then tank-side modules/kits; the tank assembly itself is the last resort. Confirm the DEF split (reservoir kit 2011 vs 2012-2016, harness 2011-2014 vs 2015-2016) against the build before ordering.
Parts
- Duramax LML DEF Tank Reservoir Wiring Harness 2011-2014 (OEM) - DEF tank harness, early window (23323441) (qty 1)
- Duramax LML DEF Tank Reservoir Wiring Harness 2015-2016 (OEM) - DEF tank harness, late window (23366892) (qty 1)
- Duramax LML DEF Tank Reservoir Kit 2011 (OEM) - DEF reservoir kit, 2011-only (84412929) (qty 1)
- Duramax LML DEF Tank Reservoir Kit 2012-2016 (OEM) - DEF reservoir kit, 2012-2016 (84412924) (qty 1)
- Duramax LML DEF Tank Module (OEM) - DEF tank module (20760381) (qty 1)
- Duramax LML DEF Pump/Module Kit (OEM) - DEF pump/module kit (22902634) when dosing pressure fails (qty 1)
- Duramax LML DEF Tank Assembly (OEM) - DEF tank assembly (22968922) when heater elements/sensors test bad (qty 1)
Install order
- read the DEF DTC family and test the heater circuit before ordering - heater opens vs dosing faults vs level/quality lies
- harness first (year-split): the chafe/short that mimics every other DEF fault
- reservoir kit / tank module (year-split reservoir: 2011 vs 2012-2016)
- pump/module kit for dosing-pressure faults; tank assembly last, then fill fresh sealed DEF
Expected outcome
DEF dosing in spec, no heater codes, no countdown timers.
Do not
- do not chase doser faults with fresh DEF alone - crystallization needs the hardware fixed too
Parts budget
About $110-$470 in parts. It depends on what the diagnosis finds; each option below is what you buy together. Prices marked "at Dave's" are Dave's Auto Center's, the same as in his store; the others are approximate prices from OEM and maker catalogs, rounded (a manufacturer's list price can run higher). Parts only, no labor.