Bulletin No.: 15-NA-010

Service Bulletin

Date: May, 2025

INFORMATION
Subject:
Attention:

Brand:

Buick
Cadillac
Chevrolet
GMC

Information for New Vehicles with Less than 1,000 Miles that May Not Pass
California Smog Inspection or Smog Inspection in Other States
Depending on the State, this testing is identified as Emissions Inspection,
Smog Check, Smog Inspection or Smog Testing.
Model:

GM
Passenger
Cars and
Trucks

Involved Region or Country

Model Year:

VIN:

from

to

from

to

2015

2026

—

—

Engine:

Transmission:

Gasoline

—

United States

Important: Service agents must comply with all International, Federal, State, Provincial, and/or Local laws
applicable to the activities it performs under this bulletin, including but not limited to handling, deploying,
preparing, classifying, packaging, marking, labeling, and shipping dangerous goods. In the event of a
conflict between the procedures set forth in this bulletin and the laws that apply to your dealership, you
must follow those applicable laws.

Catalyst Break-In Period Information
Notice:
• The catalyst break-in period has been approved by the California Air Resources Board (CARB) but
vehicles operating within the break-in period may still be subject to an inspection within California’s
Smog Inspection Program.
• The catalyst break-in period concern has been most prevalent in California because they have a Smog
Inspection I/M Readiness Policy that allows only the Evaporative Monitor to not be ready on newer model
year vehicles. This concern has occurred in other states and is expected to occur more frequently as
other States adopt a similar Smog Inspection policy.
• When presenting a new vehicle for the California Smog Inspection or for a Smog Inspection in another State,
some vehicles with less than 1,000 miles (1,609 km), may not report an Inspection/Maintenance System Check
Monitor Complete Yes status as required to Pass the Smog Inspection. This may be caused by the engine
control module (ECM) disabling some of the post catalyst oxygen sensor diagnostics until a preset catalyst
break-in period (which varies by model and vehicle) has been completed. The post catalyst oxygen sensor
diagnostics must report an Inspection/Maintenance System Yes (O2S/HO2S Monitor Complete — Yes) to the
Smog Inspection test equipment, but cannot do so until after the preset calibrated catalyst break-in period has
been completed.
In order to complete this catalyst break-in period, advise the Customer to operate their vehicle using the New
Vehicle Break-In procedure as outlined in their Owner Manual.
• In some cases passing the Smog Inspection may be required for vehicle registration of brand new 50 State
vehicles. This can happen in the following ways:
− Any time a vehicle is sold, delivered or registered outside of the GM dealer network (i.e., a vehicle sold
through a broker, drop shipped, or upfit and delivered through an upfitter) are among some of the possible

Copyright 2025 General Motors. All Rights Reserved.

Page 2

May, 2025

Bulletin No.: 15-NA-010

examples meeting the California Registration definition for new vehicles delivered outside of the California
Dealer network.
− A new vehicle is purchased in another state and is temporarily registered in that state before being brought
into California.
⇒ If this occurs, a Smog Inspection is required in California. However, the vehicle will not be ready for the
Smog Inspection until after the catalyst break-in period has been completed.
Customer Options to Resolve the Case of a New Vehicle Not Being Ready for the California Smog Inspection
When the vehicle is not ready for the Smog Inspection, the customer has a few options to resolve the situation as
follows:
1. Obtain a Temporary Operating Permit from the California Department of Motor Vehicles, which will allow the
customer to drive the vehicle allowing in many cases for the problem to resolve itself.
2. The customer can work with a GM Dealer to make sure the catalyst break-in period has completed and the
O2S/HO2S Monitor Complete has been set to Yes, which could take 700–1000 miles of vehicle operation.
3. In California, the customer can call 1-800-622-7733 to make an appointment with the California Bureau of
Automotive Repair (BAR) Referee Scheduling Center in order to get a waiver from the Oxygen Sensor Monitor
Complete requirement.
In other states, for Smog Inspection/Emissions Testing requirements, refer to the various websites contained within
this Bulletin in the section titled: Smog Inspection, Emissions Inspection Website Information.

Service Procedure
Notice: This is not a warranty repair.
Verify that the vehicle owner has operated their vehicle for a minimum of 400 miles (644 km) using the New Vehicle
Break-In procedure as outlined in the appropriate Owner Manual. New vehicles may not be able to complete the
Inspection/Maintenance System Check for certain HO2S 2 diagnostics prior to 700 miles (1,127 km) and could
require 1,000 miles (1,609 km) or more of catalyst break-in depending on driving conditions.
Observe the following O2S/HO2S Monitors on the scan tool. They must set to Yes in order to Pass the Smog
Inspection:
• O2S/HO2S Monitor Complete
• O2S/HO2S Monitor Complete This Ignition Cycle
• O2S/HO2S Monitor Enabled
• O2S/HO2S Monitor Enabled This Ignition Cycle
Once the vehicle has reached 400 miles (644 km), perform the following:
1. When it is safe to do so, perform several deceleration maneuvers from a minimum speed of 45 mph (72 km/h)
for at least 10 seconds. Repeat this maneuver 3 to 4 times. Stop the vehicle and turn the ignition OFF. Perform
this complete Step three additional times.
Note: Decelerate/coast with no or limited brake input. Moderate to heavy braking can cause downshifts and
the Diagnostic test will abort.
Note: Decelerate/coast for at least 10 seconds at 0% Throttle Pedal.
2. Use a scan tool to verify the O2S/HO2S Monitors have set to Yes.
⇒

If the O2S/HO2S Monitors have not set to Yes, then continue mileage accumulation and if possible repeat
the verification every 100 miles (160 km).

3. Once a scan tool indicates that all O2S/HO2S Monitors are set to Yes, the vehicle is prepared for the Smog
Inspection.
Note: At the time this was written, the California Smog Inspection only allows the EVAP Readiness Monitor
to not be set to Yes and still pass the Smog Inspection.
⇒

If Readiness Monitors other than the O2S/HO2S Monitors are not set to Yes, refer to the Inspection/Maintenance Complete System Set Procedure in SI.

Bulletin No.: 15-NA-010

May, 2025

Page 3

GDS 2 HO2S 2 Break-In Period Remaining Parameter

4535162

Typical view of the GDS 2 HO2S 2 Break-In Period Remaining parameter. The parameter Range is from 100% to
0%, indicating a fully green catalyst to a completely broken-in catalyst, respectively. This parameter is not available
on every vehicle/engine.

Smog Inspection and Emissions Inspection Website Information
State laws regarding vehicle testing known as Smog Inspection, Emissions Inspection, Smog Testing and/or Smog
Check vary by individual State. The following websites are examples of readily available information, but are not
recommendations.
-

http://www.smogcheck.ca.gov/ This website includes all information regarding the California Smog Check
Program.

-

http://traffic.findlaw.com/drivers-license-vehicle-info/state-emissions-standards-and-testing.html Includes links to
all 50 State emissions testing regulations websites.

-

http://www.dmv.org/ This is a privately owned website and is not owned or operated by any State Agency.

-

http://www.mytime.com/guide/Smog-Check/Articles/find-out-your-states-smog-check-requirements-with-thisquick-and-easy-reference-guide

-

https://www.colorado.gov/pacific/cdphe/emissions-testing-changes-2015 General emissions inspection requirements and information.

-

https://dmv.ny.gov/inspection/inspection-requirements New York State Department of Motor Vehicles Inspection
Requirements.

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May, 2025

Bulletin No.: 15-NA-010

Version Information
Version

6

Modified

Revised August 16, 2016 – Updated the Subject, added the 2017 Model year, added an
Attention statement. Added section: Catalyst Break-In Period Information. Added a Notice
List. Replaced GDS 2 Parameters “Oxygen Sensor Readiness Monitor” with O2S/HO2S
Monitor. Added section: GDS 2 HO2S 2 Break-In Period Remaining Parameter including
a graphic. Added Website Information.
Revised June 05, 2018 – Added the 2018-2019 Model Years and clarified some of the
text.
Revised January 23, 2020 – Added the 2020 Model Year and a Involved Region or
Country section.
Revised September 23, 2021 – Added the 2021-2022 Model Years.
Revised May 07, 2025 – Added the 2023-2026 Model Years and Important statement.

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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