Service Bulletin

Bulletin No.:

20-NA-085

Date:

April, 2020

TECHNICAL
Subject:

Malfunction Indicator Lamp (MIL) Illuminated - DTCs P0018, P0019 and/or P0300 Set

Brand:

Model:

Buick

Enclave

Cadillac
Chevrolet

XTS
Impala

Model Year:
from

Date Breakpoint:
to

from

to

Traverse

2019
2020
2020

Transmission:

LFY

2020
2019

Engine:

January
2, 2019

March
1, 2020

LFX
LFX
LFY

Involved Region or Country

North America
Uzbekistan, Russia, Middle East, Israel, Palestine, Chile (West), Colombia (West), Peru
(West), Cadillac Korea (South Korea), Other Africa

Condition

Some customers may comment on a MIL illuminated.
Some customers may also comment that a misfire can be felt.
Some technicians may find one or more of the following DTCs set as active or stored in
history:
• P0300: Engine Misfire Detected
• P0018: Crankshaft Position - Intake Camshaft Position Not Plausible Bank 2
• P0019: Crankshaft Position - Exhaust Camshaft Position Not Plausible Bank 2

Copyright 2020 General Motors LLC. All Rights Reserved.

Page 2

April, 2020

Bulletin No.: 20-NA-085

Cause

5577608

This condition may be caused by a missing timing chain guide insert.
– Some engines built between 1/2/2019 and 3/1/2020, an inset was left off the far-left
primary timing chain guide for the left primary timing chain. After a period of time, the
timing chain wears through the guide support aluminum which leaves the timing chain
very loose and the engine base timing will be off.
Note: Some technicians may find when performing a compression test, a lower than
normal compression reading may be found across bank 2.

Correction

Perform an inspection:
1. Remove the B2 (left) camshaft cover and look down at the timing chain on the
left side.
2. Inspect to see if the chain is rubbing against the engine block and cylinder head.
3. Inspect for slight damage to the block or head.
– Some damage may be present but should not be detrimental to engine longevity.

⇒ If a repair is required:
•
•
•
•
•

Replace the left timing chain
Replace the left timing chain guide
Replace the left timing chain tensioner
If necessary, remove the oil pan and clean the metal out of the pan and pickup screen.
Perform an oil and filter change and ensure no further concerns with this vehicle

Bulletin No.: 20-NA-085

April, 2020

Page 3

Service Procedure
Refer to Secondary Timing Chain Guide Replacement Left Side and Camshaft Timing Chain Components
Installation in SI.

Parts Information
Causal
Part

Description

Part
Number

Qty

X

Guide, TMG
CHAIN

12600461

1

N/A

CHAIN, CM/SHF
INTER DRV
(SECONDARY)

12637743

1

N/A

TENSIONER,
TMG CHAIN
(SECONDARY)

12609261

1

N/A

FILTER, OIL

N/A

Oil

Refer
to EPC

Refer to SI

Warranty Information
For vehicles repaired under warranty, use:
Labor Operation

Description

Labor Time

4063880

Secondary Camshaft Intermediate Drive Chain Replacement Left Side

Use the Published Labor
Operations Time

Version

1

Modified

Released April 08, 2020

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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