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2013 MERCEDES-BENZ SL550

Owner reports · Recalls · Investigations

Limited comparison data

There is not enough comparable history to draw a useful model-year comparison.

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Owner complaints by model year

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Counts vary with age, sales and reporting. They are not failure rates.

What owners reported most

All reported categories

Tap a category to read its complaints. One report may name several components.

When problems were reported

Mileage at the reported incident

Limited mileage data: 11 of 17 reports include usable mileage. There isn’t enough coverage to show a useful chart.

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.

  • Steering. Review the 5 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
  • Engine. Review the 4 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →
  • Power Train. Review the 4 owner reports in this category and discuss these concerns during a pre-purchase inspection. Read reports →

NHTSA owner reports · September 18, 2026 snapshot.

1 crash reports0 fire reports0 injury reports

What owners actually said

17 reports
Mileage unknown · Mar 28, 2025
Engine

I was driving on a country road when all of a sudden my car lost power all the warning lights camo on the dashboard. Smoke started billowing out from the back and front of the car. It turned off and I only coasted about a 100 feet. I could not safely pull off to the side of the road as the car had no power. Thankfully the road w…

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I was driving on a country road when all of a sudden my car lost power all the warning lights camo on the dashboard. Smoke started billowing out from the back and front of the car. It turned off and I only coasted about a 100 feet. I could not safely pull off to the side of the road as the car had no power. Thankfully the road was not very busy and the tow truck collected the vehicle. Upon further inspection I saw a lot of oil on the road and the mechanics were able to confirm that the engine block was cracked and there were 2 large holes. Upon further research I was able to find a lot of similar cases with this specific M278 Mercedes engine and premature failures that happen because of bad cylinder coating. In later engines they update the cylinder lining to a more durable steel sleeves. I think this is a very well documted issue and a huge safety risk. There is a class action lawsuit running about the M278 engine and I think you need to get involved and hold Mercedes accountable for their poor design.

NHTSA ODI #11651239

60,000 miles · Dec 9, 2024
Steering

The contact owns a 2013 Mercedes-Benz SL550. The contact stated while driving at an undisclosed speed, the vehicle lost power steering assist functionality. There was no warning light illuminated. The vehicle was taken to an independent mechanic, who determined that the steering rack needed to be replaced. The vehicle was not re…

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The contact owns a 2013 Mercedes-Benz SL550. The contact stated while driving at an undisclosed speed, the vehicle lost power steering assist functionality. There was no warning light illuminated. The vehicle was taken to an independent mechanic, who determined that the steering rack needed to be replaced. The vehicle was not repaired. The contact related the failure to NHTSA Campaign Number: 16V899000 (Steering); however, the VIN was not included in the recall. The manufacturer was made aware of the failure but informed the contact that there was no recall associated with the VIN. The failure mileage was approximately 60,000.

NHTSA ODI #11629693

Mileage unknown · Jun 7, 2024
Suspension

The rear subframe experienced excessive levels of rust which caused the rear left side to suddenly collapse. After the collapse, the car would fish tail at low speeds (i.e., less than 15 miles per hour). I am thankful that the collapse did not happen when traveling at higher speeds such as an expressway, which would have certain…

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The rear subframe experienced excessive levels of rust which caused the rear left side to suddenly collapse. After the collapse, the car would fish tail at low speeds (i.e., less than 15 miles per hour). I am thankful that the collapse did not happen when traveling at higher speeds such as an expressway, which would have certainly caused an accident. The Mercedes Benz dealer refused to cover the cost of the work to replace/repair the subframe. The dealer stated that they would cover the cost under an “extended warranty” if the car was manufactured for the US, but, as I found out, the car was made for Canada based on the VIN #. This is the case even though the subframe in this model had the same rusting issue in the US and in Canada. Additionally, I purchased the car in Florida. I am surprised that there had not been a full recall on this issue especially since it appears to impact over 500,000 Mercedes cars. Drivers are on the road with this issue and are unaware of this issue unless they happen to bring their car in for service specifically for this issue. Additionally, not honoring the recall for the car because it was made for Canada even though I am a US Citizen, the car was purchased in the US, and the car operates in the US does not make sense. This issue is a hazard on US roads, and should be proactively communicated and remediated. Not doing so poses a safety issue. I am further surprised that the Department of Transportation has not taken an active role in this issue.

NHTSA ODI #11593024

Mileage unknown · Apr 12, 2024
Power Train

Started the vehicle and used the gear selector to shift to Drive. Car did not go into gear. Towed to dealer. Dealer found faulty “ism module.” Apparently a very common issue with these cars. So common that the part is in an “indefinite back order.” The replacement part is also revised because Mercedes knows there was a manufact…

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Started the vehicle and used the gear selector to shift to Drive. Car did not go into gear. Towed to dealer. Dealer found faulty “ism module.” Apparently a very common issue with these cars. So common that the part is in an “indefinite back order.” The replacement part is also revised because Mercedes knows there was a manufacturer defect with the existing part. I am being charged more than $1600 on a part that the manufacturer has already acknowledged was faulty and created a replacement for it.

NHTSA ODI #11582692

Mileage unknown · Dec 29, 2021
Steering

Our power steering went out all of a sudden. We took this to our mechanic who said it was a recall for the power steering. Fletcher Jones Mercedes' looked at the vehicle did a computer update recall and said the power steering is not covered. The car is very unsafe and we need this fixed.

NHTSA ODI #11445443

Mileage unknown · Nov 30, 2021
Engine

Cam sensor seals failed which leaked oil into the wire harness, O2 sensors, and ECM. This happens to be a common problem with M278 engine. The repair was $10,217 to fix this issue. The car would not pass emissions without this repair. Could oil into the electrical system pose a fire hazzard?

NHTSA ODI #11442087

65,000 miles · Jun 1, 2021
Steering

The contact owns a 2013 Mercedes-Benz SL550. The contact stated while the vehicle was being serviced at a tire shop, he was informed that the power steering assist warning light was illuminated. The steering wheel became difficult to turn. The contact took the vehicle to the local dealer to be diagnosed. The contact was informed…

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The contact owns a 2013 Mercedes-Benz SL550. The contact stated while the vehicle was being serviced at a tire shop, he was informed that the power steering assist warning light was illuminated. The steering wheel became difficult to turn. The contact took the vehicle to the local dealer to be diagnosed. The contact was informed that the steering assembly needed to be replaced. Upon investigation, the contact associated the failure with NHTSA Campaign Number: 16V899000 (Steering) however, the VIN was not included. The vehicle was not repaired. The manufacturer was informed of the failure. The failure mileage was approximately 65,000.

NHTSA ODI #11419160

36,800 miles · Apr 8, 2020
Service BrakesCrash

JUN 2017: ANNUAL SERVICE. ASK TO HAVE BRAKES CHECKED BECAUSE BRAKE PEDAL WAS TRAVELLING DOWN TO THE FLOOR. JUN 2018: ANNUAL SERVICE. COMPLAINT: BRAKE PEDAL WOULD HIT THE FLOOR AND AS IT TRAVELED DOWN FURTHER, THE ENGINE ACCELERATION TICKED-UP, AT WHICH TIME I RELEASED THE BRAKE PEDAL AND RE-APPLIED THE BRAKES SUCCESSFULLY.…

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JUN 2017: ANNUAL SERVICE. ASK TO HAVE BRAKES CHECKED BECAUSE BRAKE PEDAL WAS TRAVELLING DOWN TO THE FLOOR. JUN 2018: ANNUAL SERVICE. COMPLAINT: BRAKE PEDAL WOULD HIT THE FLOOR AND AS IT TRAVELED DOWN FURTHER, THE ENGINE ACCELERATION TICKED-UP, AT WHICH TIME I RELEASED THE BRAKE PEDAL AND RE-APPLIED THE BRAKES SUCCESSFULLY. JUN 2019: ANNUAL SERVICE: STRONG COMPLAINT: DITTO JUN 2018 EXCEPT AS THE BRAKE PEDAL APPROACHED THE FLOOR, THE ENGINE ACCELERATION WAS INCREASING. 12 MAR 2020: ACCIDENT: TIME 0645 AM PST, TRAVELING WEST-BOUND ON A NEAR-STRAIGHTAWAY (SLIGHT 5-DEGREE CURVE TO THE LEFT) AT 40 MPH IN A 50 MPH ZONE ON A 6-LANE ROADWAY, IN FAR-RIGHT LANE WITH 8-CAR-LENGTHS TO THE CAR AHEAD, I APPLIED THE BRAKES AS THE CARS AHEAD OF ME SLOWED TO A STOP IN THE RIGHT LANE. I CONTINUED INCREASING PRESSURE ON THE BRAKES UNTIL THE PEDAL WAS ON THE FLOOR, THE ANTI-LOCK BRAKES SYSTEM NEVER ENGAGED AND AT ABOUT 20-FT TO THE CAR AHEAD, THE ENGINE RPM TOOK OVER DEFEATING THE WHOLE BRAKE SYSTEM RESULTING IN MY CAR ACCELERATING AND SMASHING INTO THE CAR STOPPED AHEAD OF MY CAR. IN HIND-SIGHT, I FOUND OUT THAT M-B OF SAN DIEGO SERVICE DEPT. NEVER PERFORMED A DRIVE-TEST TO CHECK-OUT MY REQUESTS BUT INSTEAD PERFORMED A STANDARD BRAKE-PADS & FLUID-LEVEL CHECK AND RETURNED THE CAR TO ME IN AS-IS CONDITION. UNTIL 12 MAR, THIS PROBLEM OF THE BRAKES TRAVELING TO THE FLOOR BEFORE THE RPM-INCREASE ENGAGED HAD BEEN UNDER CONTROL, BEING MOST NOTICEABLE AT LOW SPEEDS OF 10-12 MPH IN THE COSTCO PARKING LOT THRU-WAYS AT WHICH TIME I HAD AMPLE DISTANCE TO RELEASE THE BRAKES, DISENGAGE THE RPM-INCREASE AND RE-APPLY THE BRAKES. IT APPEARS M-B TOOK MY REQUESTS AND COMPLAINTS IN A LESS THAN LITERAL SENSE OR URGENCY.

NHTSA ODI #11320598

31,000 miles · Apr 27, 2019
Wheels

AUTO MOVING AND NOT MOVING. MY HUSBAND IS OCD AND VERY PARTICULAR ABOUT OUR VEHICLES. I HAD A FLAT TIRE ON A RUN FLAT AND DAMAGED MY LEFT DRIVER'S SIDE BACK WHEEL. WE DECIDED TO REPLACE ALL 4 TIRES AND THAT WHEEL. MY SPOUSE REMOVED ALL 4 WHEELS FROM VEHICLE, CLEANED AND INSPECTED EACH WHEEL AND WE CAREFULLY PUT THEM IN THE B…

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AUTO MOVING AND NOT MOVING. MY HUSBAND IS OCD AND VERY PARTICULAR ABOUT OUR VEHICLES. I HAD A FLAT TIRE ON A RUN FLAT AND DAMAGED MY LEFT DRIVER'S SIDE BACK WHEEL. WE DECIDED TO REPLACE ALL 4 TIRES AND THAT WHEEL. MY SPOUSE REMOVED ALL 4 WHEELS FROM VEHICLE, CLEANED AND INSPECTED EACH WHEEL AND WE CAREFULLY PUT THEM IN THE BACK OF OUR TRUCK. I TOOK THEM TO ALDERSON MERCEDES IN LUBBOCK. I WATCHED AS MONTE THE SERVICE ADVISER CAREFULLY REMOVED ALL 4 WHEELS. LATER IN THE DAY ALDERSON CALLS AND SAYS THAT THE RIGHT BACK WHEEL HAS A CRACK IN IT AND NEEDS TO BE REPLACED. I'M FLABBERGASTED AS I KNEW IT DIDN'T BEFORE I BROUGHT IT. BUT ITS A HE SAID SHE SAID. UPON RESEARCHING THE INTERNET FOR COMPLAINTS OF MERCEDES BENZ WHEELS CRACKING I FOUND A LOT OF THEM, ENOUGH FOR A CLASS ACTION SUIT. THE PROBLEM IS WHEN NEW RUN FLAT TIRES WHICH ARE EXTREMELY TOUGH ARE INSTALLED IT IS SO DIFFICULT THAT THEY CRACK. THIS IS A DEFECT OF THE WHEEL, NOT THE TECHNICIAN. I'M AFRAID THAT IF THEY CRACK THIS EASILY WHEN JUST PUTTING A NEW TIRE ON THEM, THAT THEY WILL CRACK WHILE DRIVING ON THEM. IF THIS HAPPENS THEN THE VEHICLE IS UNSAFE TO DRIVE. PLEASE LOOK INTO THE STRESS FRACTURE PROPERTIES OF MERCEDES BENZ WHEELS. I THINK THERE IS A POTENTIAL SAFETY HAZARD ISSUE. I DID NOT DRIVE OVER A POT HOLE, SO I KNOW AS OTHER COMPLAINTANTS KNOW THIS IS A MANUFACTURING ISSUE.

NHTSA ODI #11204109

31,000 miles · Apr 27, 2019
Steering

MY CAR HAD 30,000 MILES ON IT WHEN THE STEERING MECHANISM QUIT WORKING UP AND DOWN. IT TURNS OUT THE PROBLEM IS IN THE FORM OF IMPROPER INSTALLATION. THERE WAS NOTHING WRONG WITH THE PART. PART NO. 231 460 02 31. THIS PROBLEM OCCURRED AT THE FACTORY. THE TECHNICIAN OVER SHOT THE ADJUSTMENT LENGTH ON INSTALLATION, CAUSING THE…

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MY CAR HAD 30,000 MILES ON IT WHEN THE STEERING MECHANISM QUIT WORKING UP AND DOWN. IT TURNS OUT THE PROBLEM IS IN THE FORM OF IMPROPER INSTALLATION. THERE WAS NOTHING WRONG WITH THE PART. PART NO. 231 460 02 31. THIS PROBLEM OCCURRED AT THE FACTORY. THE TECHNICIAN OVER SHOT THE ADJUSTMENT LENGTH ON INSTALLATION, CAUSING THE POWER STEERING WHEEL ADJUSTMENT UP AND DOWN TO OCCUR INTERMITTENTLY. IT GETS STUCK IN THE UP POSITION MAKING IT VERY DIFFICULT TO EXIT THE CAR, ESPECIALLY IF YOU ARE A BIG PERSON. ALL MY HUSBAND HAD TO DO TO FIX IT WAS READJUST THE LENGTH AND IT WAS FIXED. THERE ARE THOUSANDS OF COMPLAINTS WHERE OWNERS ARE PAYING FOR NEW PARTS AND INSTALLATIONS AND THERE IS NOTHING WRONG WITH THE ORIGINAL PART. UNLESS YOU FIXED IT YOURSELF YOU WOULD NOT KNOW THIS. PLEASE LOOK INTO THIS AS I HAD TO PAY FOR A PART $160.65,$140 DIAGNOSIS FEE, AND MY HUSBAND HAD TO TAKE 4 HOURS OF HIS TIME TO FIX SOMETHING THAT WAS IMPROPERLY INSTALLED AT THE FACTORY. CAR IN ALL STAGES OF MOVEMENT.

NHTSA ODI #11204106

Official recalls

3

19V787000 · Communication

Nov 1, 2019

Mercedes-Benz USA, LLC. (MBUSA) is recalling certain 2013-2017 vehicles due to a software fault that may cause the date and time for the emergency call system (eCall) to differ from the actual date and time, potentially relaying an inaccurate vehicle location. For a full list of the affected models visit: https://static.nhtsa.gov/odi/rcl/2019/RMISC-19V787-4620.pdf

Consequence & remedy

Consequence: An inaccurate vehicle location may delay emergency responders, increasing the risk of injury.

Remedy: MBUSA has initiated an Over the Air (OTA) remote update. MBUSA will also notify owners, and dealers will check software for a successful OTA or update the communication module software as needed, free of charge. The recall began December 23, 2019. Owners may contact MBUSA customer service at 1-800-367-6372. MBUSA's number for this recall is 2019120008.

16V899000 · Steering:electric Power Assist System

Dec 14, 2016

Mercedes-Benz USA, LLC. (MBUSA) is recalling certain model year 2013-2015 SL550, 2013-2014 SL63 AMG, 2014-2016 E350, 2014 E350 Cabriolet, E350 Coupe, 2014-2015 S550, 2015 E350 Bluetec, 2015-2016 E400, 2016 E550 Coupe, and Maybach S600 vehicles manufactured August 23, 2012, to August 14, 2015. The affected vehicles use an electric power steering system that may have improperly soldered contacts inside the control unit, potentially resulting in the power steering system deactivating while driving.

Consequence & remedy

Consequence: If the control unit pins lose connection, there would be a loss of electric power steering assist, increasing the risk of a crash. The increase in pin contact resistance can also increase the risk of a fire, even while the vehicle is parked and ignition is off.

Remedy: MBUSA will notify owners, and dealers will replace the electric power steering control unit, free of charge. The recall began October 13, 2017. Owners may contact MBUSA customer service at 1-800-367-6372.

13V542000 · Air Bags:side/window

Nov 1, 2013

Mercedes-Benz (Mercedes) is recalling certain model year 2013 SL63, SL550, and SL65 vehicles manufactured January 16, 2013, through April 30, 2013. The affected vehicles are equipped with an occupant classification system (OCS) that may not detect a very light person sitting in the front passenger seat.

Consequence & remedy

Consequence: If the OCS does not detect a very light person sitting in the seat, the passenger side air bag would be turned off. In the event of a crash necessitating side air bag deployment, the passenger would be at an increased risk of injury.

Remedy: Mercedes will notify owners, and dealers will replace the passenger side seat cushion including the OCS. The recall began on December 20, 2013. Owners may contact Mercedes at 1-201-573-0600.

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.