Service Repair

Chevy Vehicles’ Relief Valve May be Sticking

Nov. 2, 2020

This bulletin applies to 2019 Chevy Express, Silverado and Suburban vehicles, equipped with a 6.0L L96 engine.

This bulletin applies to 2019 Chevy Express, Silverado and Suburban vehicles, equipped with a 6.0L L96 engine.

A vehicle may have a concern of no oil pressure and/or DTC P0521 set. The relief valve in the oil pump may be sticking, or the number 1 main bearing may be damaged.

Check the engine oil dipstick to confirm that the oil level is not under or overfilled. Confirm oil pressure at the main gallery with a manual gauge.

If pressure is lower than specification, replace the oil filter. If no improvement is found, remove the oil pan and inspect for number 1 main bearing damage.

If the bearings are OK, change the oil pump. According to GM, Chevrolet engineering is currently working on a root cause.

About the Author

Information courtesy of Mitchell 1

Information for Technical Service Bulletins comes from ProDemand, Mitchell 1's auto repair information software for domestic and import vehicles. Headquartered in San Diego, Mitchell 1 has provided quality repair information solutions to the automotive industry since 1918.

About the Author

Mike Mavrigian | Motor Age Editor

Mike Mavrigian has written thousands of automotive technical magazine articles involving a variety of specialties, from engine building to wheel alignment, and has authored more than a dozen books that crisscross the automotive spectrum. Mike operates Birchwood Automotive, an Ohio shop that builds custom engines and performs vintage vehicle restorations. The shop also features a professional photo studio to document projects and to create images for articles and books.