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2010 MERCEDES-BENZ GLK350

Owner reports · Recalls · Investigations

More warning signs than most GLK350 years

Owner complaints for the 2010 MERCEDES-BENZ GLK350 are substantially higher than the model-year median of 114.

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When problems were reported

Mileage at the reported incident

72 reports with mileage · 169 unknown

NHTSA’s mileage field refers to the reported incident, not necessarily the filing date. This shows report counts, not the likelihood of a failure.

What to inspect

Issues worth paying extra attention to based on owner reports.

  • Air Bags. Review the 149 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
  • Fuel/propulsion System. Review the 26 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
  • Suspension. Review the 14 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →

NHTSA owner reports · September 18, 2026 snapshot.

12 crash reports2 fire reports6 injury reports

Fuel/propulsion System complaints

26 reports
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Mileage unknown · Sep 26, 2024
Fuel/propulsion System

Extremely Urgent Safety Warning! Similar to the the passenger fuel filter extended warranty on the passenger side, the driver's side plastic fuel filter pump is obviously visably defective and forming a large crack, thereby leaking a significant amount gasoline into the back seat, with much also draining out the bottom of the ve…

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Extremely Urgent Safety Warning! Similar to the the passenger fuel filter extended warranty on the passenger side, the driver's side plastic fuel filter pump is obviously visably defective and forming a large crack, thereby leaking a significant amount gasoline into the back seat, with much also draining out the bottom of the vehicle. Additionally, the metal studs securing the filter are painted, making removal of the filter difficult without breaking the studs. No warning lamps or messages.

NHTSA ODI #11616548

Mileage unknown · Jan 3, 2023
Fuel/propulsion System

Gas leak when filling tank with fuel. Last year I had fuel pump replacement Smells like gas in my garage and I noticed leak This is not good

NHTSA ODI #11499861

Mileage unknown · Nov 25, 2022
Fuel/propulsion SystemUnknown Or Other

Mold in a/c

NHTSA ODI #11494866

Mileage unknown · Jul 18, 2022
Fuel/propulsion System

Due to the same defect Mercedes issued a recall for on the 2011 GLK, the fuel and sender pumps cracked due to a product defect causing gasoline to leak out of the vehicle as well as into the vehicle. The leak is near the exhaust causing a high degree of risk for car fire. Online research reveals numerous 2010 GLK owners with t…

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Due to the same defect Mercedes issued a recall for on the 2011 GLK, the fuel and sender pumps cracked due to a product defect causing gasoline to leak out of the vehicle as well as into the vehicle. The leak is near the exhaust causing a high degree of risk for car fire. Online research reveals numerous 2010 GLK owners with the same issue at various points in the life of the vehicle.

NHTSA ODI #11474578

Mileage unknown · May 27, 2022
Fuel/propulsion System

When my child was riding in the same car with me, my car suddenly died due to all fuel leaked out. Our car ran out of gas because all fuel were leaked. We can smell gas inside the cabin. Initially I thought car died because we ran out of the gas. After receiving 2 gallon gasoline from the tow truck, we saw dripping gasoline fro…

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When my child was riding in the same car with me, my car suddenly died due to all fuel leaked out. Our car ran out of gas because all fuel were leaked. We can smell gas inside the cabin. Initially I thought car died because we ran out of the gas. After receiving 2 gallon gasoline from the tow truck, we saw dripping gasoline from the bottom of the car when the car engine is on. I am glad it did not happen to me on the highway or there was no fire sparkles near by. My car is only 110K miles with no accident record. I do not expect a car has a defective hazard like this. People could be killed. We took the car to the dealership. Fuel Pump Assembly 221-470-17-90-28 and Fuel Filter Unit221-470-17-90-28 will be replaced. Benz has recalled 2011 model. I have news below, " The specific models are the 2011-2012 C300, GLK350, E350, S400 Hybrid, S550, S63 AMG, CL550 and CL63 AMG, but only those built from April 18, 2011, through July 12, 2011. Mercedes says there are some 5,800 vehicles affected by the latest recall in the U.S. the unit may crack when operated in high temperatures. This may cause fuel to leak, which could then cause a fire." My question is, why my 2010 model was not recalled? They were using same parts. If my car's parts has the defect, which caused "fuel to leak, which could then cause a fi re." for just under 110K miles, why nhtsa does not do anything to prevent this happen? If you search "Fuel leaking benz" , you will see tons of consumer complains. I could have ended up die if I was not lucky. Fuel pump is a critical part, it should not drip gasoline. Can you force Benz to take action before people died?

NHTSA ODI #11466431

Mileage unknown · Sep 18, 2021
Fuel/propulsion System

Two fuel tank leaks that are a fire hazard. First one was around fuel pump, cracks in plastic flange. Had repaired with a sealant. Recently another leak around the filler tube. Leak around passenger side rear wheel when filling tank. Strong smell of gasoline if not completely filled to cause leak. I would think a dangerous fire …

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Two fuel tank leaks that are a fire hazard. First one was around fuel pump, cracks in plastic flange. Had repaired with a sealant. Recently another leak around the filler tube. Leak around passenger side rear wheel when filling tank. Strong smell of gasoline if not completely filled to cause leak. I would think a dangerous fire hazard. I see recalls for other year models, but not 2010, even though basically identical.

NHTSA ODI #11433426

Mileage unknown · Jul 21, 2021
Fuel/propulsion System

String gas smell from under the car, found the fuel pump cover cracked and seal faulty

NHTSA ODI #11425776

Mileage unknown · May 19, 2021
Fuel/propulsion System

Lately, everytime I filled up the gas tank, I can smell gas from the rear left area. After some time when the tank is maybe a little over half the smell is gone. I assume there is a leak somewhere from the fill pipe to the tank. Maybe a bad rubber connector, gasket/seal failure? The vehicle has never been involved in any cras…

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Lately, everytime I filled up the gas tank, I can smell gas from the rear left area. After some time when the tank is maybe a little over half the smell is gone. I assume there is a leak somewhere from the fill pipe to the tank. Maybe a bad rubber connector, gasket/seal failure? The vehicle has never been involved in any crash. Normal usage. Low mileage. Should this be covered by MB warranty at no cost to the owner? Thank you.

NHTSA ODI #11417835

93,215 miles · Jul 10, 2020
Fuel System, OtherFuel/propulsion System

PLASTIC SEAL ON GASKETS FOR GAS TANK FAILED ON BOTH SIDES OF CAR. CAUSES LEAKING OF FUEL AND ODOR INTO PASSENGER AREA OF VEHICLE AND DANGER OF EXPLOSION DUE TO LEAKING FUEL. IT OCCURS WHEN GAS TANK IS MORE THAN 3/4 FULL TO FULL OF FUEL.

NHTSA ODI #11338640

81,000 miles · Dec 30, 2019
Fuel/propulsion System

EVERY TIME I FILL UP MY MERCEDES GLK 350 WITH FUEL THERE IS A VERY STRONG ODOR OF FUEL IN MY GARAGE AFTER I PARK THE CAR. THERE IS NO VISIBLE LEAK OF FUEL ON THE GARAGE FLOOR OR NOTIFICATION OF ANY ISSUE ON THE DASHBOARD. THE STRONG FUEL ORDER GOES AWAY AFTER DRIVING THE CAR AND BURNING OFF A GALLON OR SO. THIS IS A SERIOUS S…

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EVERY TIME I FILL UP MY MERCEDES GLK 350 WITH FUEL THERE IS A VERY STRONG ODOR OF FUEL IN MY GARAGE AFTER I PARK THE CAR. THERE IS NO VISIBLE LEAK OF FUEL ON THE GARAGE FLOOR OR NOTIFICATION OF ANY ISSUE ON THE DASHBOARD. THE STRONG FUEL ORDER GOES AWAY AFTER DRIVING THE CAR AND BURNING OFF A GALLON OR SO. THIS IS A SERIOUS SAFETY AND HEALTH ISSUE THAT STARTED FEW WEEKS AGO AND IS OF A BIG CONCERN TO ME AND TO MY FAMILY.

NHTSA ODI #11292018

Official recalls

5

19V010000 · Air Bags:frontal:passenger Side:inflator Module

Jan 9, 2019

Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2014 C250, C300 4Matic, C350, C63 AMG, E350 4Matic Coupe, E350 Cabrio, E350 Coupe, SLS AMG Cabrio, SLS AMG Coupe, 2014-2015 C250 Coupe, C350 4Matic Coupe, C350 Coupe, C63 AMG Coupe, GLK 350, GLK250 BlueTec 4Matic, GLK350 RWD, 2015-2017 E400 4Matic Coupe, E400 Cabrio, E400 Coupe, 2014-2017 E550 Cabrio, and 2014-2016 E550 Coupe vehicles sold, or ever registered, in the states of AL, CA, FL, GA, HI, LA, MS, SC, TX, PR, AS, GU, the MP, and VI or "Zone A." Additionally, MBUSA is recalling certain 2012-2014 C250, E350 4Matic Coupe, SLS AMG Cabrio, 2012-2015 C250 Coupe, C350 4Matic Coupe, C350 Coupe, C63 AMG Coupe, 2011 C300, 2011-2014 C300 4Matic, C350, C63 AMG, E350 Cabrio, E350 Coupe, SLS AMG Coupe, 2015-2016 E400 4Matic Coupe, E400 Cabrio, E400 Coupe, 2011-2016 E550 Cabrio, E550 Coupe, 2011-2015 GLK350 4Matic, GLK350 RWD, and 2013-2015 GLK250 BlueTec 4Matic vehicles ever registered in the states of AZ, AR, DE, DC, IL, IN, KS, KY, MD, MO, NE, NV, NJ, NM, NC, OH, OK, PA, TN, VA, and WV or "Zone B." MBUSA is also recalling certain 2012-2014 C250, E350 4Matic Coupe, SLS AMG Cabrio 2012-2015 C250 Coupe, C350 4Matic Coupe, C350 Coupe, C63 AMG Coupe, 2010-2011 C300, 2010-2014 C300 4Matic, C350, C63 AMG, E350 Coupe, 2011-2014 E350 Cabrio, SLS AMG Coupe, 2015-2016 E400 4Matic Coupe, E400 Cabrio, E400 Coupe, 2016-2017 E550 Cabrio, 2010-2016 E550 Coupe, 2010-2015 GLK350 4Matic, GLK350 RWD, and 2013-2015 GLK250 BlueTec 4Matic vehicles ever registered in the states of AK, CO, CT, ID, IA, ME, MA, MI, MN, MO, NH, NY, ND, OR, RI, SD, UT, VT, WA, WI and WY or "Zone C." These vehicles are equipped with air bag inflators assembled as part of the passenger frontal air bag modules that may explode due to propellant degradation occurring after long-term exposure to high absolute humidity, temperature and temperature cycling.

Consequence & remedy

Consequence: An inflator explosion may result in sharp metal fragments striking the passenger or other occupants resulting in serious injury or death.

Remedy: MBUSA will notify owners, and dealers will replace the passenger frontal air bag module, free of charge. The recall began March 29, 2019. Owners may contact MBUSA customer service at 1-800-367-6372.

18V043000 · Air Bags:frontal:passenger Side:inflator Module

Jan 10, 2018

Mercedes-Benz USA, LLC (MBUSA) is recalling certain 2013 C250, C250 Coupe, C350 Coupe 4Matic, C300 4Matic, C350, C350 Coupe, C63 AMG, C63 Coupe, E350 Cabrio, E350 Coupe, E550 Cabrio, E350 Coupe 4Matic, E550 Coupe, GLK350 4Matic, GLK250 Bluetec 4Matic, GLK350, SLS Coupe, SLS AMG GT Coupe, and SLS Roadster vehicles sold, or ever registered, in the states of Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, South Carolina, Texas, Puerto Rico, American Samoa, Guam, the Northern Mariana Islands (Saipan), and the U.S. Virgin Islands or "Zone A." Additionally, MBUSA is recalling certain 2010 C300, C300 4Matic, C63 AMG, E350 Coupe, E550 Coupe, GLK350, and GLK350 4Matic vehicles ever registered in the states of Arizona, Arkansas, Delaware, District of Columbia, Illinois, Indiana, Kansas, Kentucky, Maryland, Missouri, Nebraska, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, and West Virginia or "Zone B." MBUSA is also recalling certain 2009 C300, C300 4Matic, C63 AMG, and C350 vehicles ever registered in the states of AK, CO, CT, ID, IA, ME, MA, MI, MN, MO, NH, NY, ND, OR, RI, SD, UT, VT, WA, WI and WY or "Zone C." In the event of a crash necessitating deployment of the passenger frontal air bag, these passenger air bag inflator may explode due to propellant degradation occurring after long-term exposure to absolute humidity and temperature cycling.

Consequence & remedy

Consequence: An inflator explosion may result in sharp metal fragments striking the driver or other occupants resulting in serious injury or death.

Remedy: MBUSA will notify owners, and dealers will replace the passenger frontal air bag module, free of charge. Mercedes issued an interim notification to owners on February 23, 2018. A second notice will be mailed when remedy parts are available. Owners may contact MBUSA customer service at 1-877-496-3691.

16V363000 · Air Bags:frontal:passenger Side:inflator Module

May 26, 2016

Mercedes-Benz USA, LLC (MBUSA) is recalling certain model year 2008-2011 C300 Sedan, C300 4matic Sedan, C350 Sedan, C63 AMG Sedan vehicles, 2010-2011 GLK350, GLK350 4-Matic and E350 Coupe vehicles, 2011 SLS AMG, E350 Convertible, E550 Coupe and E550 Convertible vehicles originally sold, or ever registered, in Alabama, California, Florida, Georgia, Hawaii, Louisiana, Mississippi, South Carolina, Texas, Puerto Rico, American Samoa, Guam, the Northern Mariana Islands (Saipan), and the U.S. Virgin Islands, or "Zone A." Additionally, unless included in "Zone A" above, MBUSA is recalling certain model year 2008 C300 Sedan, C350 Sedan, C63 AMG Sedan and C300 4-Matic Sedan vehicles originally sold, or ever registered, in Arizona, Arkansas, Delaware, District of Columbia, Illinois, Indiana, Kansas, Kentucky, Maryland, Missouri, Nebraska, Nevada, New Jersey, New Mexico, North Carolina, Ohio, Oklahoma, Pennsylvania, Tennessee, Virginia, and West Virginia, or "Zone B." Vehicles not originally sold or ever registered in either Zones A or B are not subject to this safety recall. These vehicles are equipped with certain air bag inflators assembled as part of the passenger frontal air bag modules, and used as original equipment or replacement equipment. In the event of a crash necessitating deployment of the front air bags, these inflators may rupture due to propellant degradation occurring after long-term exposure to absolute humidity and temperature cycling.

Consequence & remedy

Consequence: An inflator rupture may result in metal fragments striking the vehicle occupants resulting in serious injury or death.

Remedy: MBUSA will notify owners, and dealers will replace the passenger frontal air bag modules, free of charge. Owners were sent an interim notification October 2016. A second notice will be mailed when remedy parts are available. Owners may contact MBUSA customer service at 1-877-496-3691.

16V081000 · Air Bags:frontal:driver Side:inflator Module

Feb 11, 2016

Mercedes-Benz USA, LLC. (MBUSA) is recalling certain model year 2009-2010 ML320 BlueTec 4Matic, GL320 BlueTec 4Matic and R320 CDI 4Matic, 2011 E350 Cabriolet and E550 Cabriolet, 2009-2011 ML350, ML350 4Matic, ML550 4Matic, ML63 AMG, and C63 AMG, 2010-2011 ML450 4Matic Hybrid, E350 Coupe, E350 4Matic, E550 Coupe, E550 4Matic, and E63 AMG, 2011-2012 GL350 BlueTec 4Matic and R350 BlueTec 4Matic, 2009-2012 GL450 4Matic, GL550 4Matic and R350 4Matic, 2007-2008 SLK280, SLK350, and SLK55 AMG, 2011-2014 SLS AMG Coupe, 2012 SLS AMG Cabriolet, 2013-2014 SLS AMG GT and SLS AMG GT Cabriolet, 2005 C230 Kompressor and C320, 2006-2007 C230, 2006-2011 C350, 2008-2011 C300 and C300 4Matic, 2010-2012 GLK350 and GLK350 4Matic and 2007-2008 Chrysler Crossfire vehicles. Upon deployment of the driver's frontal air bag, excessive internal pressure may cause the inflator to rupture.

Consequence & remedy

Consequence: In the event of a crash necessitating deployment of the driver's frontal air bag, the inflator could rupture with metal fragments striking the driver or other occupants resulting in serious injury or death.

Remedy: MBUSA will their notify owners, and Fiat Chrysler will notify the affected Chrysler owners. Dealers for the respective brands will replace the driver's frontal air bag module, free of charge. This recall began November 2016. Mercedes-Benz owners may contact MBUSA customer service at 1-800-367-6372 and Chrysler owners may contact Fiat Chrysler customer service at 1-800-853-1403.

15V711000 · Air Bags:frontal:sensor/control MODULE-INACTIVE

Oct 27, 2015

Mercedes-Benz USA, LLC. (MBUSA) is recalling certain model year 2008-2009 C300 Sedan, C300 4Matic, C63 AMG, and C350 vehicles, and 2010 GLK350 and GLK350 4Matic vehicles. Due to a manufacturing error, the air bag control unit may corrode and cause the control unit to malfunction.

Consequence & remedy

Consequence: The malfunctioning air bag control unit may cause the air bags to unexpectedly deploy increasing the risk of injury and the possibility of a vehicle crash. Alternatively, the air bag control unit malfunction may cause the air bags to not deploy in the event of a crash necessitating air bag deployment, increasing the risk of occupant injury.

Remedy: MBUSA will notify owners, and dealers will inspect the air bag control unit and replace it, as necessary, free of charge. Mercedes-Benz issued an interim notification to owners on December 23, 2015. The recall began on March 14, 2016. Owners may contact MBUSA customer service at 1-800-367-6372.

Model-level recall history does not show whether a particular VIN is affected or has received a repair. Check a VIN with NHTSA ↗

NHTSA investigations

1

EA21002 · Desiccated Air Bag Inflator Rupture

Opened Sep 17, 2021 · No close date supplied

Status: open (inferred from source dates) · Air Bags:frontal:driver Side:inflator Module; Air Bags:frontal:passenger Side:inflator Module

From 2000 through 2017, Takata produced millions of air bag inflators using two types of phase-stabilized ammonium nitrate ("PSAN") propellant -- propellant 2004 and propellant 2004L. After prolonged exposure to high temperature cycles and humidity, inflators using propellant 2004 can degrade, causing the propellant to burn too quickly when ignited. The rapid burning can cause the inflator to rupture during deployment, potentially causing serious or even fatal injury to vehicle occupants. See 2016 Blomquist Report at www.nhtsa.gov/sites/nhtsa.gov/files/documents/expert_report-hrblomquist.pdf.Consequently, all frontal inflators using propellant 2004 that do not contain a "desiccant" (a substance that traps and holds moisture) in US vehicles are under recall. These "non-desiccated" inflators either have been or are required to be replaced.In some cases, the remedy part for these recalled inflators was, or will be, an inflator using either propellant 2004 or 2004L that does contain a desiccant. None of these "desiccated" remedy parts (which were installed in older model year vehicles) are currently under recall for a degradation concern. Certain subsets of desiccated PSAN inflators using propellant 2004 for use as original equipment, however, have been recalled for a degradation concern. All Takata inflators produced with propellant 2004L contain desiccant, and none of these desiccated inflators using propellant 2004L are under recall for a degradation concern. There have been no reported field ruptures in any non-recalled desiccated PSAN inflators.It is understood that desiccants fully saturate at some threshold, at which point any additional moisture will not be captured. This means the degradation process observed in non-desiccated inflators using propellant 2004 may also occur in non-recalled desiccated inflators using propellant 2004, assuming additional moisture enters the inflator and high temperature cycling occurs. Based on available information, desiccant saturation can occur within the first five years in the worst environments, and the time required for full saturation is affected by multiple factors. While no present safety risk has been identified, further work is needed to evaluate the future risk of non-recalled desiccated inflators using propellant 2004.Three entities -- Takata (now known as TK Global), the Independent Testing Coalition, and Exponent -- have been studying the long-term behavior of Takata desiccated PSAN inflators using propellant 2004L (as well as 2004) in the presence of moisture and temperature cycling. The research efforts, which include development of predictive modeling techniques and field sample analysis, are ongoing. To date, none of the researchers have identified field evidence showing that propellant 2004L is undergoing a degradation process that leads to aggressive deployment and potential rupture. However, the time in service of such inflators remains short compared to that of the inflators using propellant 2004. Further study is needed to assess the long-term safety of desiccated inflators using propellant 2004L.The Office of Defects Investigation is opening this investigation to examine whether a safety defect related to propellant degradation exists in non-recalled desiccated PSAN frontal inflators manufactured by Takata. This investigation will require extensive information on Takata production processes and surveys of inflators in the field. Lists of recall actions that may have used desiccated PSAN inflators as remedy parts, as well as the makes and models originally manufactured with them, is available with the downloadable version of this document (see nhtsa.gov/recalls?nhtsaId=EA21002 -- note this information is subject to change/revision as the investigation proceeds). This investigation does not supersede EA15-001, which remains open.

Additional source detail variants (2)

Air Bags:frontal:driver Side:inflator Module

From 2000 through 2017, Takata produced millions of air bag inflators using two types of phase-stabilized ammonium nitrate ("PSAN") propellant -- propellant 2004 and propellant 2004L. After prolonged exposure to high temperature cycles and humidity, inflators using propellant 2004 can degrade, causing the propellant to burn too quickly when ignited. The rapid burning can cause the inflator to rupture during deployment, potentially causing serious or even fatal injury to vehicle occupants. See 2016 Blomquist Report at www.nhtsa.gov/sites/nhtsa.gov/files/documents/expert_report-hrblomquist.pdf.Consequently, all frontal inflators using propellant 2004 that do not contain a "desiccant" (a substance that traps and holds moisture) in US vehicles are under recall. These "non-desiccated" inflators either have been or are required to be replaced.In some cases, the remedy part for these recalled inflators was, or will be, an inflator using either propellant 2004 or 2004L that does contain a desiccant. None of these "desiccated" remedy parts (which were installed in older model year vehicles) are currently under recall for a degradation concern. Certain subsets of desiccated PSAN inflators using propellant 2004 for use as original equipment, however, have been recalled for a degradation concern. All Takata inflators produced with propellant 2004L contain desiccant, and none of these desiccated inflators using propellant 2004L are under recall for a degradation concern. There have been no reported field ruptures in any non-recalled desiccated PSAN inflators.It is understood that desiccants fully saturate at some threshold, at which point any additional moisture will not be captured. This means the degradation process observed in non-desiccated inflators using propellant 2004 may also occur in non-recalled desiccated inflators using propellant 2004, assuming additional moisture enters the inflator and high temperature cycling occurs. Based on available information, desiccant saturation can occur within the first five years in the worst environments, and the time required for full saturation is affected by multiple factors. While no present safety risk has been identified, further work is needed to evaluate the future risk of non-recalled desiccated inflators using propellant 2004.Three entities -- Takata (now known as TK Global), the Independent Testing Coalition, and Exponent -- have been studying the long-term behavior of Takata desiccated PSAN inflators using propellant 2004L (as well as 2004) in the presence of moisture and temperature cycling. The research efforts, which include development of predictive modeling techniques and field sample analysis, are ongoing. To date, none of the researchers have identified field evidence showing that propellant 2004L is undergoing a degradation process that leads to aggressive deployment and potential rupture. However, the time in service of such inflators remains short compared to that of the inflators using propellant 2004. Further study is needed to assess the long-term safety of desiccated inflators using propellant 2004L.The Office of Defects Investigation is opening this investigation to examine whether a safety defect related to propellant degradation exists in non-recalled desiccated PSAN frontal inflators manufactured by Takata. This investigation will require extensive information on Takata production processes and surveys of inflators in the field. Lists of recall actions that may have used desiccated PSAN inflators as remedy parts, as well as the makes and models originally manufactured with them, is available with the downloadable version of this document (see nhtsa.gov/recalls?nhtsaId=EA21002 -- note this information is subject to change/revision as the investigation proceeds). This investigation does not supersede EA15-001, which remains open.

Air Bags:frontal:passenger Side:inflator Module

From 2000 through 2017, Takata produced millions of air bag inflators using two types of phase-stabilized ammonium nitrate ("PSAN") propellant -- propellant 2004 and propellant 2004L. After prolonged exposure to high temperature cycles and humidity, inflators using propellant 2004 can degrade, causing the propellant to burn too quickly when ignited. The rapid burning can cause the inflator to rupture during deployment, potentially causing serious or even fatal injury to vehicle occupants. See 2016 Blomquist Report at www.nhtsa.gov/sites/nhtsa.gov/files/documents/expert_report-hrblomquist.pdf.Consequently, all frontal inflators using propellant 2004 that do not contain a "desiccant" (a substance that traps and holds moisture) in US vehicles are under recall. These "non-desiccated" inflators either have been or are required to be replaced.In some cases, the remedy part for these recalled inflators was, or will be, an inflator using either propellant 2004 or 2004L that does contain a desiccant. None of these "desiccated" remedy parts (which were installed in older model year vehicles) are currently under recall for a degradation concern. Certain subsets of desiccated PSAN inflators using propellant 2004 for use as original equipment, however, have been recalled for a degradation concern. All Takata inflators produced with propellant 2004L contain desiccant, and none of these desiccated inflators using propellant 2004L are under recall for a degradation concern. There have been no reported field ruptures in any non-recalled desiccated PSAN inflators.It is understood that desiccants fully saturate at some threshold, at which point any additional moisture will not be captured. This means the degradation process observed in non-desiccated inflators using propellant 2004 may also occur in non-recalled desiccated inflators using propellant 2004, assuming additional moisture enters the inflator and high temperature cycling occurs. Based on available information, desiccant saturation can occur within the first five years in the worst environments, and the time required for full saturation is affected by multiple factors. While no present safety risk has been identified, further work is needed to evaluate the future risk of non-recalled desiccated inflators using propellant 2004.Three entities -- Takata (now known as TK Global), the Independent Testing Coalition, and Exponent -- have been studying the long-term behavior of Takata desiccated PSAN inflators using propellant 2004L (as well as 2004) in the presence of moisture and temperature cycling. The research efforts, which include development of predictive modeling techniques and field sample analysis, are ongoing. To date, none of the researchers have identified field evidence showing that propellant 2004L is undergoing a degradation process that leads to aggressive deployment and potential rupture. However, the time in service of such inflators remains short compared to that of the inflators using propellant 2004. Further study is needed to assess the long-term safety of desiccated inflators using propellant 2004L.The Office of Defects Investigation is opening this investigation to examine whether a safety defect related to propellant degradation exists in non-recalled desiccated PSAN frontal inflators manufactured by Takata. This investigation will require extensive information on Takata production processes and surveys of inflators in the field. Lists of recall actions that may have used desiccated PSAN inflators as remedy parts, as well as the makes and models originally manufactured with them, is available with the downloadable version of this document (see nhtsa.gov/recalls?nhtsaId=EA21002 -- note this information is subject to change/revision as the investigation proceeds). This investigation does not supersede EA15-001, which remains open.