6.6L V8 Gasoline Engine Exchange

The 6.6L V8 gasoline engine (RPO L8T) (Fig. 20) available on 2020 Silverado 2500/3500 and Sierra 2500/3500 models is now under the engine exchange program for the 2020 model year.


Fig. 20


The engine exchange program is administered by the GM Product Quality Center (PQC). Dealerships are required to call the PQC, not GM Technical Assistance (TAC), to request an exchange. Prior to calling the PQC, complete the OEM Engine Exchange worksheet in #PIP5656. The information on the worksheet will minimize the time spent on the telephone and avoid the need of a second call to the PQC.

The PQC may refer the technicians to TAC if additional diagnosis is required. TAC will be available for product inquiries that do not require assembly replacement. Engine block and internal components along with any component in which a cylinder head has to be removed to perform the repair will require an engine exchange.

The following serviceable components may be removed and serviced without exchange.

  • Accessory Drive
  • A/C Compressor
  • All Engine Sensors
  • All Cooling System Hoses
  • Brackets
  • Camshaft Covers
  • Coolant Pump
  • Coolant System Bypass Pipe
  • Coolant System Radiator Inlet/Outlet Pipes
  • Coolant Outlet Assembly
  • Crankshaft Damper
  • Engine Control Module (ECM)
  • Engine Cover / Beauty Cover
  • Engine Mounts/Transaxle Mounts
  • Engine Oil Cooler
  • Engine Wiring Harness
  • Exhaust Manifold / Gasket
  • Flywheel / Flex Plate
  • Fuel Injectors
  • Fuel Injector Wiring Harness
  • Fuel Rail
  • Fuel Pipes & HP Fuel Pump Assembly
  • Generator
  • Hi / Lo Pressure Fuel Lines
  • Heater Outlet / Inlet Fittings
  • Ignition System (Coil, Spark Plugs)
  • Intake Air Ducts and related components
  • Intake Air Temperature Sensor
  • Intake Manifold
  • Knock Sensors
  • MAP or Baro Sensor
  • Mass Air Flow Sensor
  • Oil Fill Cap
  • Oil Filter
  • Oil Level Indicator and Tube
  • Oil Pressure Switch
  • Oil Pressure Control Solenoid Valve
  • PCV Hose(s)
  • PCV System
  • Starter Motor Assembly
  • Thermostat Housing/Gasket
  • Throttle Body/Related Components
  • Vacuum Pump and Lines
  • Vapor Vent Lines/Seals


Engine Broadcast Code

The engine broadcast code, which is needed on the engine exchange worksheet, can be found in two locations on the engine.

The engine broadcast code is located near the front of the engine, on the right-hand side of the block. (Fig. 21)


Fig. 21


The engine broadcast code also is located on the rear of the engine on the left-hand cylinder head. (Fig. 22)


Fig. 22


If diagnosis leads to replacing the 6.6L V8 engine assembly, contact the PQC by opening a new case using the Dealer Case Management (DCM) system. From the DCM home page, click New PQC Case on the Technical Assistance tab.

TIP: Do not clear any DTCs prior to contacting the PQC.

Refer to #PIP5656 for additional information about completing the necessary forms for an engine exchange.


– Thanks to Tim Lightfoot

Throttle Body Connector Terminal Tension
Whine Sound from Under Vehicle

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