20NA161

Service Bulletin
Bulletin No.:
20-NA-161
Date:
May, 2021
INFORMATION
Subject:
Brand:
Chevrolet
Information on Engine Low Oil Pressure Indicator on the Driver Information Center
(DIC) - DTC P0521 Set
Model:
to
Express
2020
3500/4500 Medium
Duty (LCF)
2019
Silverado 2500/3500
GMC
Model Year:
from
2019
2019
Suburban
2019
Savana
2020
Sierra 2500/3500
2019
Date Breakpoint:
from
to
-
-
Engine:
Transmission:
6.0L
(L96 LC8)
-
Involved Region or Country
North America, Middle East, Iraq, Israel, Palestine, Chile (West), Peru (West), Thailand
(ASEAN)
Condition
Some customers may comment on one or more of the following conditions:
• MIL is illuminated.
• Oil Pressure Indicator on.
Some customers may also comment that the MIL illuminates and then turns off.
Some technicians may find DTC P0521 (Engine Oil Pressure Sensor Performance)
active or stored in history in the Engine Control Module (ECM).
Cause
This condition may be caused by a sticking oil pressure relief valve within the oil pump
assembly.
If you encounter a vehicle with the above DTC or conditions and before replacing any
parts, it will be necessary to follow the steps below to determine what failure mode may
exist and what the correct repair procedure is:
⇒ Remove the oil level indicator and confirm the oil level is at the full mark and
not overfilled.
Correction
Copyright 2021 General Motors LLC. All Rights Reserved.
If oil level is full, it will be necessary to follow the steps below:
– Inspect the #1 main bearing for any damage.
• If the #1 main bearing is not damaged, then it will be necessary to replace the
engine oil pump only.
• If the #1 main bearing is damaged but not spun it will be necessary to replace the
crankshaft, main bearings, rod bearings and the engine oil pump.
• If the #1 main bearing was spun it will be necessary to replace the engine
assembly.
When the applicable repair is complete road test vehicle to ensure engine is operating as
designed.
Page 2
May, 2021
Parts Information
Causal
Part
Description
Part
Number
Qty
X
PUMP, OIL
12696357
1
N/A
ENGINE,
GASOLINE
(SERV NEW) L96
19256594
1
ENGINE,
GASOLINE
(SERV NEW) LC8
12642269
1
CRANKSHAFT,
(CROSS
DRILLED
CRANK)
12685656
1
BEARING KIT,
CR/SHF
(STD) (#3)
89017572
1
BEARING KIT,
CR/SHF (#1,2,4,
5) (STD)
89017571
4
BEARING KIT,
CONN
ROD (STD)
89017573
8
N/A
GASKET,
OIL PAN
12612350
1
N/A
SEAL, O/PMP
SUC PIPE
(0-RING)
12584922
1
HOUSING, CR/
SHF RR
OIL SEAL
12639250
1
GASKET, CR/
SHF RR OIL
SEAL HSG
12639249
1
BOLT, CR/SHF
BALR
(M16x2.0x103)
12557840
1
STUD, CR/SHF
BRG CAP (HFH,
M10x2x23)
12560273
10
BOLT, CR/SHF
BRG CAP (SIDE)
(SHORT)
(M8x1.25x11)
12556127
10
BOLT, CR/SHF
BRG CAP
(M10x2x102.5)
12560272
10
GASKET, ENG
FRT CVR
12633904
1
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
N/A
Bulletin No.: 20-NA-161
Bulletin No.: 20-NA-161
May, 2021
Page 3
Warranty Information
Note: Only use the Labor Operation number that
coincides with the repair performed.
For vehicles repaired under warranty, use:
Labor Operation
Description
4066070
Oil Pump Replacement
4067490
Engine Replacement
4066750
Crankshaft Replacement
Labor Time
Use the Published Labor
Operations Time
Version
2
Modified
Released November 30, 2020
Revised May 10, 2021 - Removed the Breakpoint Date, Changed the Correction section
information and added #3 Crankshaft Bearing Part to Parts Information section.
GM bulletins are intended for use by professional technicians, NOT a "do-it-yourselfer". They are written to inform these
technicians of conditions that may occur on some vehicles, or to provide information that could assist in the proper
service of a vehicle. Properly trained technicians have the equipment, tools, safety instructions, and know-how to do a
job properly and safely. If a condition is described, DO NOT assume that the bulletin applies to your vehicle, or that your
vehicle will have that condition. See your GM dealer for information on whether your vehicle may benefit from the
information.
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