Bulletin No.: 25-NA-066

Service Bulletin

Date: March, 2025

INFORMATION
Subject:
Brand:

Chevrolet

GMC

Diagnostic Tip Diesel Inspection/Maintenance System Status Parameters
Model:

Model Year:

Build Date:
from

Engine:

from

to

to

Silverado 2500 HD/
3500 HD

2024

2025

L5P

Silverado 4500 HD/
5500 HD/6500 HD

2023

2025

L5D

Sierra 2500 HD/
3500 HD

2024

2025

L5P

Transmissi
on:

Involved Region or Country

North America, Israel, Palestine, Middle East

Condition

Some customers may find that the inspection/maintenance system status parameters are
not all ready

Cause

This condition may be caused by not all the codes needed to complete the inspection/
maintenance system status parameters have run and passed

Correction

Please see below

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.

Information
In terms of I/M readiness, we are not concerned with any codes set, we want the codes to run and pass. Think of
each of the inspection/maintenance system status parameters as a single monitor. The chart in document ID
5866970 shows all the codes that need to run and pass for each to clear. Below is a drive cycle that may be useful to
clear all the inspection/maintenance system status parameters in the ECM.
Engineering has put together the following to help to get all of the inspection/maintenance system status parameters
to run and pass.
After a Code Clear: (Allows for I/M Readiness in all diagnostics but P2459)
Drive procedure needs a minimum of two, eight-hour soak periods. Choose 2/3 sections to have a soak)
1. Verify the transmission is in PARK for automatic transmissions, and neutral for manual transmissions.
2. Start the engine and idle for approximately 1-2 minutes.
3. Using the scan tool, trigger a driving regen.

Copyright 2025 General Motors. All Rights Reserved.

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March, 2025

Bulletin No.: 25-NA-066

⇒

Drive to the nearest freeway. If freeway is not close (within 3-5 minutes) please delay triggering the regen
until a parking lot close to the freeway.

⇒

For 45 minutes, the speed limit and coast down about 15 MPH (25 KPH) every 3-5 minutes. Repeat until
regeneration is complete. Try to accelerate at a constant rate after each coast down (approximately 0.5-1.5
mph per second, with the same pedal foot position), avoid fast accelerations.

⇒

Turn around at the nearest exit after the regeneration is complete.

4. Repeat Step 3 on return to the starting point but without a regen.
5. After returning to the parking lot, drive around for approximately 3-5 minutes keeping the speed under 15 MPH
(24 KPH).
6. Return and park the vehicle (do not idle more than 2 minutes) and shutoff for at least 5 minutes. If reasonable
timing, try to soak the engine for 8 hours or more.
7. Start the engine and immediately drive a city type cycle that includes stops (at least 3). If this step is being run
after an 8-hour soak, try to keep the pedal busy. Slowdown 5-10 mph (8 to 16 KMH) and speed back up. Avoid
cruising.
8. Repeat Steps 3 – 7 (Repeat only once for a total of two).
9. Drive on highways or back roads at 55 – 60 MPH (88-96 KPH) for 15 minutes.
10. After returning to the parking lot, drive around for approximately 3-5 minutes, keep the speed under 15 MPH (24
KPH).
11. Park the vehicle (do not idle for more than 2 minutes) and shut it off for at least 5 minutes. If reasonable timing,
try to soak the engine for 8 hours or more. The 8-hour engine soak is not necessary on this step if it was already
completed twice.
12. Skip this step if an 8-hour soak was not done on Step 11. Start the engine and immediately drive a city type
cycle that includes stops (at least 3). If this step is being run after an 8-hour soak, avoid cruising, and keep the
pedal busy. Slowdown 5-10 mph (8 to 16 KMH) and speed back up.
13. Park the vehicle and check I/M readiness with a scan tool if specific code is not ready see the table below.
Inspection/maintenance (I/M) status monitor parameters
Abbreviation for table below

Scan Tool Parameter

BS

Boost System Monitor - Since Diagnostic Trouble Codes
Cleared

CC

Catalytic Converter Monitor - Since Diagnostic Trouble Codes
Cleared

EA

Exhaust Aftertreatment Monitor - Since Diagnostic Trouble
Codes Cleared

EGR

Exhaust Gas Recirculation Valve/Camshaft Position Monitor Since Diagnostic Trouble Codes Cleared

EGS

Exhaust Gas Sensor Monitor - Since Diagnostic Trouble Codes
Cleared

FS

Fuel System Monitor - Since Diagnostic Trouble Codes Cleared

OSH

Oxygen Sensor Heater Monitor - Since Diagnostic Trouble
Codes Cleared

OS

Oxygen Sensor/Heated Oxygen Sensor Monitor - Since
Diagnostic Trouble Codes Cleared

PF

Particulate Filter Monitor - Since Diagnostic Trouble Codes
Cleared

If you are having issues with a particular inspection/maintenance (I/M) status monitor parameter, just run all of the
steps for the I/M Parameter listed below.

Bulletin No.: 25-NA-066

March, 2025

I/M Parameter

Code

Best drive to get
the code/
parameter to
pass.

CC

P0421

See Step 3, repeat
if diagnostic not
ready (requires 2
completions after a
code clear), if
P2002 not ready
complete Steps 3 &
4

CC

P0422

See Step 3, repeat
if diagnostic not
ready (requires 2
completions after a
code clear), if
P2002 not ready
complete Steps 3 &
4

EA

P20EE

See Step 4; can
turn around halfway
rather than driving
a full 45 minutes
one way. After step
4, please complete
Step 6 (no 8 hour
soak is necessary).
Repeat if diagnostic
not ready (requires
at least 2
completions after a
code clear).

BS

P0234

See Step 4; can
turn around halfway
rather than driving
a full 45 minutes
one way. If Step 4
is not possible try
Step 8, but may
need to double the
time; ensuring
there are
stoppages and
constant
accelerations.

BS

P026A

See Step 9.

EGS

P0299

See Step 9.

EGS

P11D3

See Step 7 or Step
9.

EGS

P11D5

See Step 9, can
use Step 7 but less
effective depending
on route.

EGS

P147B

See Step 7 or Step
9.

EGS

P1981

See Step 7 or Step
9.

EGS

P2209

See Step 7 or Step
9.

EGS

P2297

See Step 7 or Step
9.

EGS

P22A7

See Step 7 or Step
9.

EGS

P22F9

See Step 7.

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March, 2025

I/M Parameter

Code

Best drive to get
the code/
parameter to
pass.

EGS

P22FB

See Steps 9, 10
and 11. May
require an iteration
or two after code
clear, must allow
after run post key
off.

EGS

P22FE

See either Steps 9,
10, and 11 or Steps
7, 10, and 11. May
require an iteration
or two after code
clear, must allow
after run post key
off.

EGS

P24AF

Diagnostic should
run at vehicle key
on, no additional
steps needed.

EGS

P24C7

See Step 7 or Step
9.

EGS

P24D1

See Step 7 (either
include driving
around parking lot
or double the route)
or Step 8.

EGS

P24DA

See steps 6 (soak
for 8+hrs) and 7,
requires two
completions after a
code clear. Must
immediately drive
and keep a busy
pedal. The
diagnostic will run
within the first
5 minutes. Try to
find a route that
has stops/turns
within a mile of
each other.

EGS

P2A00

See Step 7 or Step
9.

EGS

P2A01

See Step 7 or Step
9.

PF

P2AB0

See Step 7 or Step
9.

PF

P144E

See Step 3 or run a
regen.

PF

P144F

See Step 3 or run a
regen.

PF

P2002

See step 4, can
turn around halfway
rather than driving
a full 35 minutes
one way. After step
4 complete step 8.
If P0421 and
P0422 are not
ready complete
step 3 & 4 together.

Bulletin No.: 25-NA-066

Bulletin No.: 25-NA-066

March, 2025

I/M Parameter

Code

Best drive to get
the code/
parameter to
pass.

PF

P2459

Requires 2 natural
regens,
approximately
800 miles a regen.
No work around for
diagnostic.

PF

P24A0

See Step 3 or run a
regen

PF

P24A1

See Step 3 or run a
regen.

EGR

P0401

See Step 7 or Step
9.

EGR

P0402

See step 9, may
need to double the
step if experiencing
issues. Try holding
the pedal position
constant on
accelerations.

EGR

P140B

See Steps 7 and 9.
Repeat or extend
steps if necessary.

EGR

P140C

See Step 7 (either
include driving
around parking lot
or double the route)
or Step 9.

EGR

P2457

See Step 7 or Step
9.

Version

1

Modified

Released March 21, 2025

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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