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/
Bosch CP4.2 contamination repair for the LML (mode Bosch CP4.2 high-pressure pump failure and fuel-system contamination): the pump's roller wears through and floods the high-pressure circuit with metal. Cut the fuel filter open first - metal means the whole tank-to-injector system gets replaced, not just the pump. This is the Duramax's defining six-figure-adjacent repair; do not rebuild around a failed pump.
Parts
- Duramax LML High-Pressure Fuel Pump Service Kit (OEM) - high-pressure pump service kit, all years (19420326) (qty 1)
- Duramax LML Fuel Injection Rail, Left (OEM) - left fuel rail - metal trap on a contaminated system (12651989) (qty 1)
- Duramax LML Fuel Injection Rail, Right (OEM) - right fuel rail - metal trap on a contaminated system (12620532) (qty 1)
- Duramax LML Fuel Injector Assembly, Reman Kit (OEM) - injector exchange pieces when debris reached the heads (19421169) (qty 8)
Install order
- cut open the fuel filter: metal particles confirm the CP4 cascade - stop cranking, the more you crank the further the debris travels
- tank drain + lines flush before any new hardware touches the system
- pump kit replacement (19420326, the all-year kit)
- rails and injector pieces only as the inspection dictates - every removed component is a debris decision
- prime per procedure, verify rail pressure, and log the repair - the contamination history matters at resale
Expected outcome
Rail pressure in spec, no metal downstream, no repeat debris.
Do not
- never bolt a new CP4 into a contaminated system - the debris kills it in hours
- do not keep cranking a no-start after a running failure
Parts budget
About $2,350-$5,000 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.