22-NA-173 Service Bulletin/Repair Instructions

Bulletin No.: 22-NA-173
Service Bulletin
Date: May, 2024
INFORMATION

Subject:
Brand:
Chevrolet
Information on Transmission Fluid Leak
Model:
Corvette
Model Year:
VIN:
from
to
from
to
2020
2024
—
—
Engine:
Transmission:
All
All
Involved Region or Country
North America, Europe, Israel, Middle East, Japan, Thailand, Australia/New Zealand
Condition
Some customers may comment that transmission fluid can be seen under the vehicle.
Information
The following photos are only for informational purposes and to help guide technicians to

known areas of possible leaks. Testing in the photos used fluorescent dye to aid in better

photography. These transmissions were scrapped after dye was added. At no time

should a technician in the field add dye to the M1L transmission. Technicians should only

follow the trace powder diagnosis procedure recommended in Fluid Leak Diagnosis.
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.
Copyright 2024 General Motors. All Rights Reserved.
Examples of Transmission Leak Areas of Concern

When performing a leak test always be sure to clean

the transmission thoroughly prior to powder testing.

Make an attempt to protect the transmission labels from

any type of solvent that may be used. Solvents can

erase the print on the labels and make the transmission

difficult to identify. A great opportunity to recreate the

leak after powder application is to perform the

Hydraulic System Flush Procedure in service information document 6412296 multiple times until a leak is

visible. Because of the elevated RPMs in this test and

the vehicle being stationary, always monitor engine

temperature. It may also be necessary to run the

vehicle with the rear wheels spinning on the lift to

reproduce the leak. It will be necessary to disable the

ABS system if this is the case. Make sure the vehicle

has been supported by the lift properly with the recommended lift attachments and that the wheels are clear

of the floor. If the coolant temperature is excessive and

fans continue to run, it may be necessary to allow the

vehicle to cool before continuing testing.
Page 2
May, 2024
Bulletin No.: 22-NA-173
6142752
A leak between sealing plate and Bell Housing.

-
If this leak is found, it will be necessary to replace

the clutch differential housing assembly. Be sure to
also order all the one-time use parts in the service

information repair instructions.
6142966
Leaks at the gasket area between the clutch and differential cover and the main case. There is a gasket in

this area.

-
The gasket in this area is serviceable. Be sure to

follow service information for which parts are onetime use and order these components. Also be

sure to inspect the machined surfaces and attempt

to verify that the leak is actually caused by the

gasket rather than a bolt torque or surface finish

issue that may cause a duplicate repair.
Video (Oil Leak) (SIO# 6460614)
Bulletin No.: 22-NA-173
May, 2024
Page 3
This video above shows transmission case porosity,

issue during testing.
4823455
6142841
This is an area that is often mis-diagnosed as a transmission cooler issue. It was found that in most cases,

leaks in this area are caused by transmission case

porosity under the transmission cooler. Proper

diagnosis in this area would be to inspect the cooler for

any signs of physical damage. If no damage is found,

carefully remove the cooler, and inspect the two (14) Orings for damage and proper sealing. The dye photo

shows a puddle of oil just under the cooler sealing
area in the pocket, the fluid is being pushed through the

case due to material porosity. This concern will require

transmission assembly replacement. This leak can

often be confused with transmission SAV cover and

MCV cover leaks because the leaking fluid from above

tends to get captured by the rails and follow that path.

Be sure to powder test these areas well and with the

understanding that fluid tends to flow down across the

transmission.
Page 4
May, 2024
Bulletin No.: 22-NA-173
6142814
A small crack in the clutch cover area (1) of the input

shaft seal can be mis-diagnosed as an input shaft seal

leak (3). Additional cases have been verified at the

input shaft end plug/seal (2), was damaged during

transmission to engine mating. The input shaft end plug

and the input shaft seal can be serviced separately if a

crack is not witnessed in the clutch cover. If the area is

cracked the clutch differential housing assembly will

need replacement as an assembly. The input shaft end

plug does not come with the clutch differential cover

assembly.
6142818
Porosity concerns with the differential cover. This area

needs to be carefully powder tested to verify the leak is

not associated with the cover seal (16) or the dogbones and seals. Technicians have stated that they

have found the cover double-gasketed when they

confused the metal differential shims with what they

thought were gaskets. All shims need to be re-installed

to retain proper bearing load on differential. If porosity

is found in the cover, the transmission will require

replacement.

Note: Due to a revision in service information, the

engine cradle no longer needs to be removed to

replace the auxiliary canister filter housing. This led to

an update in the labor time study and the labor hours

for this repair have been adjusted to reflect this.
Bulletin No.: 22-NA-173
May, 2024
Page 5
6142744
The auxiliary canister filter can create leaks in several

areas. The most common area is cover seal (20), Oring installation issues after filter replacement. Other

areas of concern can be found at the are O-rings (12)

and (17).
Note: Inspect the cover prior to replacement of the seal

for porosity issues in the O-ring groove area.
The photo above shows the red arrow pointing to a

case porosity issue that was found lying behind the

auxiliary canister housing. With any case porosity

issue, the transmission will require replacement. The

photo below shows the red arrow pointing to the

auxiliary canister filter cover O-ring groove. There have

been known cases with porosity found in the O-ring

groove causing leaks in this area.
6456550
Page 6
May, 2024
Transmission rear cover area leak. (Tremec name

plate):

• If there seems to be a leak in this area, be sure to

clean the area thoroughly. Residual oil can get

trapped between the outer surface and the O-ring.

• After powder testing, if a leak re-occurs, remove

the cover, and inspect the O-ring for damage.
Bulletin No.: 22-NA-173
• The red arrow in the graphic above, points to the

oil dam that may come off when the cover (Tremec

name plate) is removed. If it is removed, it is

necessary to replace the associated O-ring and

align properly with cover prior to re-assembly.

Damage will occur if the oil dam is not aligned to

match the cover.
• If no obvious damage is found with the O-ring, be

sure to inspect the cover itself for porosity issues in

the O-ring groove. It is critical to identify the

difference between a leak and dampness.
6637446
6142979
Bulletin No.: 22-NA-173
May, 2024
Transmission case porosity concerns have been

found in the SAV cover area of the transmission. This is

often the most misdiagnosed leak on this transmission.

The fluid seeps through the case and runs down

between the SAV cover and case to the pan rail, and

often the transmission pan, and gasket get replaced,

then the SAV cover, and finally the transmission. Often
Page 7
these leaks will not develop by just allowing the engine

to run. Usually, the vehicle will need to be lifted safely

on a hoist with the wheels raised to allow the vehicle to

run in gear. This action applies to most porosity leaks.

New Examples of Transmission Leak Areas of

Concern
6636539
Plug leakage and fluid leaking from blind holes will

require transmission replacement.
Page 8
May, 2024
Bulletin No.: 22-NA-173
6636536
Examples of case porosity in front of the SAV cover and

above that left axle stub that may present as an axle

seal leak of SAV cover leak. Powder testing should

allow identification by the technician. If leak is
porosity in these areas the transmission assembly will

need replacement.
Bulletin No.: 22-NA-173
May, 2024
Page 9
6636545
The graphics represent new areas that may exhibit

porosity. The last photos show the difference between

rear case porosity and rear cover (Tremec nameplate)

leaks.

Important: Keep in mind that adding dye to the DCT

transmission is never acceptable. These transmissions

had dye added only to highlight the photos. These

transmissions were cored after testing. If a technician

adds dye to a transmission in the field, it will be

necessary to drain and replace all the fluid at a cost to

the dealer.
Main Shaft Plug

Fluid Tubes and O-rings

MCV (main control valve) Cover and gasket

SAV (solenoid activation valve) Cover and gasket

Canister Filter housing

Canister Filter Cover

Axle Shaft Oil Seals

Cooler and O-rings
Serviceable components for leaks include:
Differential Carrier Cover Seal and O-rings (KIT 1)
Clutch Differential Housing Gasket
Rear Cover (Tremec name plate) and O-ring
Input Shaft Seal

Version
5
Modified
Released August 24, 2022

Revised June 06, 2023 – Changed Engine and Transmission RPOs to All.

Revised October 16, 2023 – Added the 2024 Model Year and Additional Information

under Examples of Transmission Leak Areas of Concern section.

Revised October 30, 2023 – Added Israel, Japan, Thailand to the Involved Region or

Country section and added a Note above the auxiliary canister filter information in the

Examples of Transmission Leak Areas of Concern section.

Revised May 10, 2024 – Added additional information throughout Examples of Transmission Leak Areas of Concern section and Added New Examples of Transmission Leak

Areas of Concern 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.
WE SUPPORT VOLUNTARY

TECHNICIAN

CERTIFICATION

SaleBestseller No. 1

OBD2 Scanner Diagnostic Tool XTOOL Anyscan A30M V2.0, 2026 Wireless Bidirectional Scan Tool with Free Updates, 26 Resets, All System for Android & iPhone, Crank Sensor Relearn, EPB, Throttle Relearn

Stay Updated with Lifetime Access: This obd2 scanner includes lifetime free software updates for all app service functions. With a single payment, enjoy full access to diagnostics, reset tools, and maintenance features — zero subscription fees. A budget-friendly choice for weekend mechanics, home car owners, and DIYers, supporting vehicles from 1996 onward. Come to us with your VIN to check compatibility.
Full Bidirectional Control/Active Tests & Stable Wireless Connectivity: This car code reader features full bidirectional control, allowing you to send commands to the vehicle's ECU for active tests on components such as fuel pumps, injectors, A/C clutches, windows, sunroofs, and more. This car scanner diagnostic tool helps DIYers quickly diagnose and test vehicle parts, cutting down troubleshooting and repair time. With BT 4.0 wireless connectivity, you can enjoy cable-free diagnostics up to 33 feet. Stand in your garage and test windows, wipers, or even engine components—all without needing to move around your car.
Portable Car Scanner with 26 Resets: Scheduled vehicle maintenance with the A30M car diagnostic scanner can keep your vehicle in peak condition and save you big on dealership trips. The XTOOL A30M obd2 scanner diagnostic tool features essential reset and relearn functions, such as Oil Reset, EPB Reset (Electronic Parking Brake Release), SAS, ABS Brake Bleeding, Throttle Body Relearn, Injector Coding, Crank Sensor Relearn, Headlight Adjustment, and Tire Size Reset. Note: Service functions may vary by vehicle model – check compatibility beforehand!
Wide Compatibility CAN FD & FCA Autoauth: This obd2 scanner diagnostic tool is compatible with over 85+ car brands from the U.S., Europe, and Asia, providing extensive coverage through a BT connection with your smartphone or iPad. Now upgraded to support the latest protocols, it includes FCA AutoAuth access for Chrysler, Jeep, Dodge, and Fiat (2018+), and supports CAN FD for GM (2020+) models, giving you greater access to newer vehicles and systems. Note: The FCA AutoAuth account is not included with the device. Users must register and pay separately through the official FCA AutoAuth website to access diagnostic functions for vehicles that require it.
Up to 8 Live Data Streams Graphing – Real-Time Graphing for Deeper Insight: This car scanner supports up to 8 live data streams simultaneously with intuitive, real-time graphing. Gain comprehensive insights into your vehicle’s performance, making it easier to spot issues, detect trends, and make informed diagnostic decisions with confidence.

SaleBestseller No. 2

XTOOL Anyscan A30D OBD2 Scanner Diagnostic Tool - Bidirectional Scan Tool Wireless - Lifetime Updates & 19 Resets Crank Sensor EPB Throttle Relearn - Full System Car Code Reader for iPhone & Android

Save $500+/Year with Pro-Level Diagnostics -No Subscriptions: The Portable XTOOL Anyscan A30D OBD2 scanner diagnostic tool includes free lifetime software updates for all app service functions, without extra cost. With a single payment, enjoy full access to diagnostics, relearn scan tools, and maintenance features. A cost-effective, smart choice for car owners and DIY enthusiasts, compatible with vehicles from 1996 onward. Please provide the car VIN and the special functions you need in advance so that we can confirm compatibility
Bi-Directional Control for Faster Troubleshooting: Unlike a basic code reader, the A30D bi directional scan tool sends commands directly to your vehicle’s ECU to actively test components like fuel pump, valves, wipers, windows, doors, sunroof, and headlamps right from your smartphone. See component responses in real time without disassembly—perfect for brake jobs, electrical issues, and hard-to-find problems. This bidirectional obd2 scanner helps pinpoint faults faster, reduce guesswork, and avoid replacing good parts. An efficient, easy-to-use car scanner diagnostic tool built for DIYers, home garage users, and small-shop technicians who want real two-way scanner, not just codes
19 Reset Functions for Routine Maintenance: The A30D car diagnostic scanner provides 19 relearn functions without extra charges, including EPB Reset for parking brake replacement, TPMS Reset after tire changes, ABS Auto Bleeding, Oil Reset, SAS Reset, BMS Reset, Throttle Relearn, Injector C0ding, Gear Learning, Crank/Crankshaft/Cam/Ckp Sensor Relearn Tool, Transmission Match, Seat Calibration, Airbag Repair and more. This XTOOL A30D automotive scanner diagnostic tool supports preventive care, helping extend vehicle life and reduce costly shop visits. Functions vary by vehicle make and year—plz confirm compatibility before purchase
Stable BT Connection & All-System & 8 Pids Live Data: The A30D wireless OBD2 scanner delivers a fast and stable wireless connection up to 33 feet, letting you move freely around the vehicle without tangled cables. Pair with with Android 9.0+ and iOS 10.0+ devices to turn your phone into a mobile auto scanner—perfect for home garages, driveways, or on-the-spot repairs. This full system scanner for cars provides real-time access to all major modules, including Engine, Gearbox, ABS, SRS, AC and more. with clear graphs, meters, and up to 8 PIDs displayed at once. This car code reader makes system monitoring visual, simple, easy to understand, and offering data logging for playback and deeper
Wide Compatibility with CAN-FD & FCA Support: The A30D car computer diagnostic reader works with most 1996 and newer vehicles with a standard OBD2 port, including for Ford, for GM, for Toyota, for Honda, for Nissan,for Hyundai etc, with ongoing updates covering more car models and functions later. It also supports newer communication protocols like CAN-FD and FCA AutoAuth (Personal AutoAuth account and active subscription required, not included with the device!for Chrysler, for Dodge, for Jeep, for Fiat models). It is a future-ready automotive scanner diagnostic tool for households with multiple vehicles or part-time techs. Coverage vary by cars, plz check the compatibility first

SaleBestseller No. 3

XTOOL D7 Bidirectional Scan Tool: 2026 Ai-Assisted OBD2 Scanner Diagnostic Tool with 36+ Resets, Full System Car Scanner with EPB, Injector Test, Throttle, Crank Sensor Relearn, FCA, CANFD & DoIP

2026 Latest Version – Now Upgraded from 32GB to 64GB: XTOOL D7 obd2 scanner diagnostic tool with bidirectional is designed for DIY enthusiasts, professional mechanics. It now offers 64GB storage for smoother operation. Its 5000mAh battery (with 2500mAh 7.3V fast-charging) supports all-day use. With FCA, CAN FD, and DOIP protocol support, it covers more vehicle models and newer systems. A newly added battery voltage reading shows battery status before diagnostics, helping prevent low-voltage tests that could harm the vehicle. The V2.0 Diagnostic Report allows shops to personalize results with logos, customer details, and attachments to build trust and maintain records.
Save $500+/Year with Pro-Level Diagnostics: Whether you're a DIYer, starting a repair business, or beginning work at an auto shop, XTOOL D7 car scanner offers advanced features typically found only in expensive professional OBD2 scanners - without the high price tag. With 4,000+ Active Tests & Bidirectional Pids, 36+ Special Functions, advanced module resets like SRS Reset, OE-level All-System Scan (one-click), FCA AutoAuth, CAN FD, DoIP, data export, and 8 PIDs graphing, the D7 auto scan tool covers 100,000+ vehicles (excluding Indian models). Includes 3-Year updates and supports the XV200 endoscope to detect em!ssions and intermittent issues.
Full Bidirectional Advantage Over Other Code Readers & Scan Tools: The XTOOL D7 automotive scanner offers true bidirectional control plus advanced bidirectional PIDs, letting you send commands to components like A/C clutches, fuel injectors, windows, fans and more, while monitoring sensor responses live to catch elusive issues (even those without warning lights). Unlike budget bidirectional obd2 scanners limited to basic active tests,the D7 car fault scanner gives you full bidirectional control to run ABS pump tests, throttle position, turn fan on/off and solenoid tests, etc. No guessing, no extra fees—just smarter diagnostics
OE-Level Full System Car Diagnostic Scanner with 8 Live Data Graphs: The XTOOL D7 is a pro-grade diagnostic tool that gives you full access to all vehicle systems—just like Snap on scanners & the factory scan tools, it delivers deep, accurate diagnostics you can trust. Easily view live data streams, retrieve freeze frame, and run active tests to pinpoint issues fast. With the ability to graph up to 8 PIDs at once, you can spot performance trends and troubleshoot like a pro. Whether you're a mechanic or car owner, with the D7 auto scanner you can stay ahead of problems and keep your vehicle running at its best
High-value Automotive Scanner Diagnostic Tool with 36+ Special Function, Module Resets, Relearns, Calibrations, Adaptations & Initializations: XTOOL D7 diagnostic tool packs 36+ common & advanced maintenance, skip the $150 fee for battery registration after replacement, throttle body relearn after cleaning, or TPMS resets post-rotation, Auto bleed after the pad changes, or Electronic Parking Brake. Need to reset the transmission after towing? Crank sensor relearn for GM/for Dodge? Done. D7 also covered advanced functions like Ad~blue Reset, VIN Write, and many more professional OBD2 scanner functions that we can't list here. Text us your VIN + what you need, we’ll check the compatibility

This product presentation was made with AAWP plugin.

Last update on 2026-05-12 / Affiliate links / Images from Amazon Product Advertising API

Buffer Email Facebook Flipboard Hacker News LinkedIn Messenger Mix Pinterest Print Reddit SMS Telegram Tumblr X VK WhatsApp Line Xing Threads Bluesky Copy Mastodon Nextdoor