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.
- 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.
- [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
- Rapid 30 sec start and 1 min leak pinpoint: Generates thick smoke in 30s, localizing leaks within 60s. Built - in air pump eliminates need for external air source. This automotive smoke machine is ideal for weekend DIYers, letting you go from power‑on to visual confirmation smoothly.
- Pinpoint EVAP & Fuel Line Micro-Leaks: Featuring high - sensitivity output,this smoke tester automotive delivers pressurized smoke to trace EVAP,fuel lines,and intake manifolds. It visually exposes hairline cracks that visual inspection misses,solving the anxiety of recurring engine warnings and unclear leak origins.
- Compatible With Multiple Vehicle Systems: Designed for automotive leak diagnostics, this smoke machine supports EVAP systems, intake manifolds, throttle body connections, vacuum hoses, and related components. Multiple adapters help simplify connections across different vehicle systems, allowing DIY vehicle owners to perform a wider range of leak inspections and maintenance tasks with a single diagnostic tool
- Built-In Air Pump for Easy Setup: No external air compressor or additional air source required. Simply connect to a 12V vehicle battery and begin leak testing, helping simplify setup and making inspections more convenient in home garages and maintenance environments
- Easy Operation for DIY Vehicle Owners: Complex diagnostic equipment can discourage routine vehicle inspections. This smoke machine requires only 10–20ml of test oil and a DC 12V power connection to begin operation. The simplified setup process helps users start EVAP leak testing, vacuum system inspection, and intake diagnostics with minimal preparation and no complicated procedures
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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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