Some 2020 Silverado, Sierra; 2020-2021 Camaro; 2021 Corvette, Tahoe, Suburban, Yukon, and Escalade models equipped with the 5.3L engine (RPOs L82, L84), 6.2L engine (RPOs L87, LT1, LT4, LT2), or 6.6L engine (RPO L8T) may have a misfire and engine noise condition. The Check Engine MIL also may be illuminated along with several possible DTCs, including DTCs P0300, P0106, P0506, P3189, P318A, P318B, P318C, P318D, P318E, P318F, and P3190. These conditions may be due to a broken valve spring.
If it’s determined during an inspection that the engine has a broken valve spring, a cylinder leakage test on the affected cylinder must be performed.
5.3L and 6.6L Engines
On 5.3L and 6.6L engines (RPOs L82, L84 and L8T) built from June 1, 2020 to October 7, 2020, if cylinder leakage is not observed, replace only the affected valve spring. (Fig. 13)
6.2L Engines
On 6.2L engines (RPOs L87, LT1, LT4 and LT2) built from June 1, 2020 to October 7, 2020, if cylinder leakage is not observed, replace all valve springs on both cylinder banks.
Fig. 13
If there is cylinder leakage in the engine, perform further diagnosis to determine the extent of the engine damage and the correct repairs required.
For 6.2L engines (RPOs L87, LT1, LT4 and LT2) that have engine damage, follow the engine restriction procedures outlined in #PIP5759.
TIP: All valve springs are requested to be sent back for further engineering analysis and inspection.
If there is a valve spring concern, contact the GM Technical Assistance Center (TAC) (U.S.) or Canadian Technical Assistance Centre for assistance with issue verification and expediting parts if needed. U.S. dealerships should create a TAC DCM case before calling TAC.
For additional information, refer to #PIP5752F.
– Thanks to Bryan Salisbury
Updated November 30, 2020
(Just to correct a comment below) A dropped valve is not always an inattentive customer. I watched one idling in a line inside the shop with the lot attendant sitting in it, and in two seconds it went from idling perfectly fine to a valve in the cylinder with the head broken off of it and a hole in the cylinder wall.
WE HAVE 2020 CAMARO IN THE SHOP WITH 66 MILES ON IT THE SPRING BROKE AND DAMAGE THE CYLINDER WALL AND PISTON ON TWO CYLINDERS AND CYLINDER HEAD METAL IN THE INTAKE ENGINE IS ON RESTRICTION
I would assume it’s to get an accurate account of how many cars are having this problem to narrow down the manufacturing location of bad springs. I have a c8 with bent valve and they will not send springs until you tell them the extent of damage. Depending on who you speak with at tac they will tell you that. First truck I had they sent them next day. Still waiting for springs for this car.
have had many trucks with this concern, including ones almost straight off the transport, one with 50 miles and one with 140 miles, have yet to have one with any damage beyond the spring itself damaged, but a dropped valve and destroyed engine is always a inattentive customer away with a broken spring, i am curious why the springs are on restriction now as per doc 5666146, is it to keep dealers from stocking up or merely slow down repairs by adding to our paperwork?