NHTSA ID Number: 10205586
Manufacturer Communication Number: 21NA267
Summary
This bulletin advises the technician of a possible location that a leak may occur from the SCT pipe.
Condition
Customer concern of smoke or exhaust fumes/odor in the cabin or exhaust fumes/odor outside the cabin.
Cause
This condition may be caused by an improper weld on the Exhaust Back Pressure Valve.
Correction
Test for a leaking exhaust backpressure valve weld joint using the Power Smoke diagnostic leak detector (GE-52250 – refer to the latest version of PIP5684).
- Please note, smoke from the tester may not get through the DPF, so test downstream by administering the smoke at the fitting on the tailpipe bladder seal.
Important: Be certain to remove the duct tape from the exhaust cooler after testing.
- Also, the tailpipe bladder seal doesn’t reach the exhaust cooler so use duct tape around the pipe to seal the cooler holes.
Repair this or any other leaks as necessary.
Refer to the pictures below and inspect the weld joint on the Exhaust Back Pressure Valve:
Note: If the weld joint is leaking, replace the Exhaust Back Pressure Valve.
- The exhaust backpressure valve is located between the downpipe from the SCR w/ filter and the under floor SCR.
A leak may be caused by an ineffective weld, allowing for a leak at the flange joint.
- Soapy water can be used to identify the leak, though smoke from the GE-52250 is also effective.
10 Affected Products
Vehicles
| MAKE | MODEL | YEAR |
CADILLAC | ESCALADE | 2021 |
| CADILLAC | ESCALADE ESV | 2021 |
| CHEVROLET | SILVERADO 1500 | 2020-2021 |
| CHEVROLET | SUBURBAN | 2021 |
| CHEVROLET | TAHOE | 2021 |
| GMC | SIERRA 1500 | 2020-2021 |
| GMC | YUKON | 2021 |
| GMC | YUKON XL | 2021 |
1 Associated Document
Manufacturer Communications
Bulletin No.: 21-NA-267
Date: November, 2021
- HyperSmoke Technology – Creates Thick Visible Smoke for Easy Leak Testing. Adjustable Pressure. Infinite Smoke. Instant Warmup. Built-In Air Compressor Motor. OEM Approved Smoke Fluid. Designed and Engineered by AutoLine Pro USA, an American Team of Individuals bringing the latest innovation to you.
- HyperSmoke Benefits – Hypersmoke never overheats, has EVAP mode to protect EVAP from permanent damage, has a mode with higher pressure to test for more leaks like boost/turbo, has a built-in air compressor, comes with proper automotive-grade leak detection fluid for safe and accurate testing, engineered in the USA with custom components and is a professional-grade tool made for serious diagnostic work.
- Includes Everything You Need – Made for ALL Leak Testing Scenarios - EVAP, Vacuum, Intake, Exhaust, Turbo, Superchargers, EGR, Cooling Systems, Engine Blocks, Oil Leaks, Body Work, Wind & Water Leaks, worn rubber, gaskets, seals, connectors, Cars, Trucks, Tractors, Semis, Motorcycles, Scientific Apparatus, and more!
- OEM Approved Smoke Fluid Included – Safe for all systems and sensors. Premium High-Smoke output formula. We’ve included plenty of fluid so you can focus on what’s important – 240 minutes of runtime!
- Adjustable Pressure – Adjustable Pressure gives you the flexibility to leak test a significantly wider array of systems ranging from EVAP all the way to Turbocharged systems. Why is this feature important? EVAP must be tested at under 1 PSI otherwise DAMAGE WILL OCCUR. This is a feature MISSING from other overseas copy-paste smoke machines.
- HyperSmoke Technology – Creates Thick Visible Smoke for Easy Leak Testing. Adjustable Pressure. Infinite Smoke. Instant Warmup. Built-In Air Compressor Motor. OEM Approved Smoke Fluid. Designed and Engineered by AutoLine Pro USA, an American Team of Individuals bringing the latest innovation to you.
- HyperSmoke Benefits – Hypersmoke never overheats, has EVAP mode to protect EVAP from permanent damage, has a mode with higher pressure to test for more leaks like boost/turbo, has a built-in air compressor, comes with proper automotive-grade leak detection fluid for safe and accurate testing, engineered in the USA with custom components and is a professional-grade tool made for serious diagnostic work.
- Includes Everything You Need – Made for ALL Leak Testing Scenarios - EVAP, Vacuum, Intake, Exhaust, Turbo, Superchargers, EGR, Cooling Systems, Engine Blocks, Oil Leaks, Body Work, Wind & Water Leaks, worn rubber, gaskets, seals, connectors, Cars, Trucks, Tractors, Semis, Motorcycles, Scientific Apparatus, and more!
- OEM Approved Smoke Fluid Included – Safe for all systems and sensors. Premium High-Smoke output formula. We’ve included plenty of fluid so you can focus on what’s important – 240 minutes of runtime!
- Adjustable Pressure – Adjustable Pressure gives you the flexibility to leak test a significantly wider array of systems ranging from EVAP all the way to Turbocharged systems. Why is this feature important? EVAP must be tested at under 1 PSI otherwise DAMAGE WILL OCCUR. This is a feature MISSING from other overseas copy-paste smoke machines.
- 【Very Cost-Effective】This smoke tester automotive is a professional diagnostic machine.The built-in air pump compressor generates 20–25 PSI of air pressure, allowing smoke to be easily introduced into the automotive system under test.It can produce a large volume of smoke within 10 seconds,fast and large smoke output, enabling you to quickly and accurately locate leaks.By rapidly identifying and repairing automotive leaks, it saves you both time and money.You can proactively detect and resolve potential issues before they turn into costly problems
- 【Include all necessary accessories】Infinite smoke for easy leak testing. Instant warmup. Built-in air compressor motor .Our automotive smoke machine includes: built-in air pump, power cord clamp, bottles (oil not included), multiple vehicle cone adapters, smoke delivery hose, intake bladder, and full-size automotive cap plugs.This product also includes a spare Bladder!You can start testing right out of the box.
- 【Wide Testing Range】The smoke machine automotive can do smoke testing of multiple systems, such as EVAP systems, Intake Systems, Cooling / EGR /Exhaust Systems, Crankcase Systems, Engine Airtightness, Vacuum Leaks, Low Pressure Turbo leaks.Applicable cars, motorcycles, snowmobiles, off-road vehicles, various pipe fitting testing, fuel tank system testing,Cars, Motorcycles,ATVs, light trucks and speedboats boats.And the smoke machine has built-in overheat protection. It will automatically shut off when too hot to protect itself.This machine has a built-in air pump. No additional air supply is needed.
- 【Easy Operation】1.Fill 10ml-15ml baby oil ( Not Included) to the smoke machine. 2. Disconnect the intake pipe of the car. Connect the intake pipe of the car with the detector. 3. Connect the detector with the DC 12V battery, and it starts to work. 4.The pipe will be filled with smoke. Check the leak points. PLEASE NOTE:when the smoke from the equipment is not obvious,new oil should be added; When working for more than3 hours, the smoke oil should be replaced. The filling of new oil should be carried out when the equipment iscooling,10-15ml each time.,and please Please bring your own baby oil or paraffin oil.
- 【Smart Protection】Compact and portable with a sleek design, this smoke leak detector automotive can be easily stored in your vehicle’s trunk for convenient use anytime, anywhere.The smoke machine has overheat and freeze protection, it will be in self-protection state after a long working time to avoid the smoke maker overheated, the indicator light will be off. And the equipment will stop making smoke, until the temperature comes to safety level. Do not fill oil while working.
- NEW BUILT-IN AIR MOTOR: No need for a separate air supply!
- HIGH PERFORMANCE, PREMIUM BUILD: Made in the USA. Solid Thick Metal Construction for durability. Equipped with our brand new AutoLine Pro Ceramic Smoke Coil and Top Rated Smoke Fluid that outputs LOTS OF SMOKE and last a Lifetime.
- PRECISE AND SAFE: Engineered to be 100% safe for all vehicles. Thick smoke output detects even the smallest leaks. A perfect complement to tools such as Fuel Pressure Testers when diagnosing EVAP and fuel-related systems.
- SIMPLE TO USE: (1) Fill with the included OEM Approved or Any Smoke Fluid. (2) Turn on the Built-In Air Motor. (3) Start smoke diagnostics!
- OEM APPROVED SMOKE FLUID INCLUDED: Safe for all systems and sensors. 800 Min Premium High-Smoke output formula. We’ve included plenty of fluid so you can focus on what’s important. ( Other brand's smoke machine just comes with EMPTY bottle)
- [Built-in Air Pump]: Smoke machine features a built-in air pump, eliminating the need for an external air source, allowing you to perform tests anytime, anywhere. Simply add about 20ml of baby oil or Glycerin (oil not included) to start your testing effortlessly
- [Multi-Function]: Suitable for a wide range of tests, including EVAP systems, vacuum leaks, low-pressure turbo leaks, intake manifolds, cooling/EGR/exhaust systems, and more. It can be used on cars, motorcycles, and various other vehicles
- [Quick Detection]: The machine generates thick smoke within just 10 seconds of startup, providing enough output to detect even the smallest leaks, ensuring fast and accurate problem identification
- [Lightweight and Portable]: Weighing only 4.4lb, the Solary automotive smoke machine is compact, easy to store, and transport, making it an essential tool for every car owner
- [User-Friendly]: With a simple and intuitive interface, the device has a low entry barrier, making it easy for even first-time users to quickly get started
Last update on 2026-05-27 / Affiliate links / Images from Amazon Product Advertising API
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Service in
Bulletin No.: 21-NA-267 INFORMATION
Date: November, 2021
Subject: Exhaust Fumes Or Odor In Cabin Or In the Engine Compartment
This bulletin replaces PIP5780. Please discard PIP5780. Brand: Model:
Model Year: from to
VIN:
from to
Engine: LM2
Transmission: Chevrolet Silverado Suburban Tahoe 2020
2021
2021 LM2 LM2 LM2 GMC
Sierra Yukon models
2020
2021
LM2 LM2 Involved Region or Country Condition Cause North America, Uzbekistan, Russia, Middle East, Israel, Palestine, Chile, Columbia, Ecuador, Paraguay, Peru, Uruguay, Japan, S. Korea, Thailand, Australia, New Zealand.
Customer concern of smoke or exhaust fumes/odor in the cabin or exhaust fumes/odor outside the cabin.
This condition may be caused by an improper weld on the Exhaust Back Pressure Valve. Page 2 November, 2021 Bulletin No.: 21-NA-267 Test for a leaking exhaust backpressure valve weld joint using the Power Smoke diagnostic leak detector (GE-52250 – refer to the latest version of PIP5684).
• Please note, smoke from the tester may not get through the DPF, so test downstream by administering the smoke at the fitting on the tailpipe bladder seal.
Important: Be certain to remove the duct tape from the exhaust cooler after testing.
• Also, the tailpipe bladder seal doesn’t reach the exhaust cooler so use duct tape around the pipe to seal the cooler holes.
Repair this or any other leaks as necessary.
Refer to the pictures below and inspect the weld joint on the Exhaust Back Pressure Valve:
Note: If the weld joint is leaking, replace the Exhaust Back Pressure Valve. Correction 5735432 • The exhaust backpressure valve is located between the downpipe from the SCR w/ filter and the under floor SCR. 5735765 • A leak may be caused by an ineffective weld, allowing for a leak at the flange joint. Bulletin No.: 21-NA-267 November, 2021 Page 3
5735764
• Soapy water can be used to identify the leak, though smoke from the GE-52250 is also effective. Version Modified 1
Released November 19, 2021
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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