Seat Heater Safety Takes a Back Seat

Four years ago, Safety Research & Strategies, along with nationally recognized burn care specialists, raised an issue long neglected by automakers and the regulators: seat heater safety. This comfort feature -- often designed to reach maximum temperatures that range far above human tolerances – can and does pose dangers to occupants, but it is rarely investigated or recalled. In 2011, we wrote an issue brief, based on our research, and challenged the industry to set standards for safe temperatures and the National Highway Traffic Safety Administration and mobility adapters to attend to the problem of burns to drivers and passengers with lower body sensory deficits.

To our pleasant surprise, the National Highway Traffic Safety Administration responded with a letter that indicated, at least, a willingness to study the issue and encourage the Society of Automotive Engineers to devise a voluntary standard. An SAE committee was duly formed, and for two years there was a flurry of publicly posted activity. And then – nothing.

The problem certainly hasn’t burned itself out. We are still documenting cases of serious injuries to individuals who cannot feel the intense heat from car seat heaters. NHTSA is still fielding complaints from consumers about seat heaters that burn through upholstery, clothing and skin, like this one from the owner of a 2007 Mercedes GL450, lodged with NHTSA earlier this month:

We had left the home - drove approximately 3 minutes at 20 miles an hour with the seat heater on. All of a sudden the seat started to smoke - it had caught fire. We had a baby in the car, were travelling down a mountain road in Aspen. We pulled over to the side of the road and thankfully were able to put the fire out with snow from a snow bank (what would have happened if it was in the summer?). There is a big hole in our car seat now and obviously - we are not able to use the seat heaters. I see from the reports here that this has happened many times with the same vehicle -- there should be a recall done for this issue on this vehicle as someone may be injured severely in the future.

Perhaps you don’t feel sorry for a person who sustains a seat heater fire in a Mercedes on a mountain in Aspen. Mercedes certainly doesn’t. The automaker has not announced a recall. In fact, Mercedes has deployed scorched-butt tactics against those who have the unmitigated temerity to complain that their seats are burning them. Consider the case of Donna Mattie, of North Andover, Mass. who suffered a back burn in her 2010 GL450 shortly after turning on her heated seat on a cool morning:

According to her legal complaint, Mercedes' technicians tested the SUV and determined that all of the temperature points within the driver's seat were operating at 120-125°F (48-51°C) while the seat heater was on its highest setting, which was within the temperature range specified by Mercedes for the 2010 Mercedes GL 450.

This is well above the human heat tolerance limits set by the ASTM of 111°F. And, Mercedes responded to Mattie’s demand for compensation by ignoring it.

Sadly, ignoring the problem seems to the first response from most of the manufacturers and the regulator.

The Outliers

A cursory review of NHTSA’s Vehicle Owner Questionnaire for any narrative concerning seat heaters or seat warmers affecting any passenger vehicle within the 2000 to 2014 model years, and, after weeding out unrelated complaints, we tallied roughly 1,800 instances in which drivers complained about seat heaters that generated enough heat to produce smoldering, smoke, flames, holes in leather upholstery, pants and coats, extreme discomfort beyond the point of human tolerance and burn injuries. Most of these were mild, because occupants who felt a burning sensation were usually able to pull over, discover the source and turn the seat heater off before it did serious damage. But not always. This complaint was lodged on January 10 by the driver of a 2006 M-series Mercedes:

Contact was driving, approx. 15 min. After engine start and seat heater turn-on. Contact felt a burning sensation on posterior/hip. Contact stopped car and got out. There was a burn hole in the driver's seat back at lower left. There were two burn holes through contact's pants. Later examination showed a second degree (blister) burn on contact's hip. This is not a warranty claim as the dealer suggests, but, rather a serious manufacturer defect that causes burn injury.

Nearly every major manufacturer was the subject of at least a few complaints – but, using raw counts, there were definite outliers. We did not refine the raw numbers; we did not try to derive rates based on the proportion of a manufacturer’s fleet with heated seats as an option or standard equipment. With that caveat, here are the winners:  Up and away, the biggest offender was, Volkswagen with 421; followed by BMW with 228 complaints; Jeep with 183; and followed by Mercedes with 136.

Industry Response

Automaker’s willingness to fix these problems has been lukewarm, at best. Some of the most recent seat heater recalls have been from manufacturers that don’t even get on the VOQ’s radar. Aston Martin, with zero complaints to NHTSA, launched a seat heater recall in December for 7,256 vehicles manufactured between 2006 and 2014. In November, Southeast Toyota, a long-time Toyota distributor based in Florida which turns a handy profit installing accessories such as seat heaters,  recalled 3,233 vehicles, covering a wide range models somewhere in the 2006-2011 model years, for the a seat cushion compression problem, which may damage the seat heater wiring.

There was a correlation, however, between manufacturers with a high number of complaints and past recalls, satisfaction campaigns and NHTSA investigations, which seem to indicate that these problems have not been resolved.

The last time BMW addressed a seat heater problem with a recall was in December 2004, when the automaker recalled 15,030 5-Series and 2,875 7-Series for a heating mat in the outboard side bolster of the seat's backrest that could fail due to mechanical loading – i.e. occupants getting in and out of the seat. It seems, as nearly 200 of the complaints we found post-date this recall by four years and into the present, that Bayerische Motoren Werke did not get all of the affected vehicles. Here’s one filed with NHTSA in January:

On a very cold day, I got into my car, and turned on the seat heater on the driver’s side of my X3. I smelled something burning and the side of my waist felt hot as if I was on fire. I realized that it must be the seat heater so I immediately turned it off. I stopped my car, got out and noticed my coat had been burnt. I noticed a burned hole on the side of my seat, in which was the cause of my coat catching fire.

Volkswagen has also made a stab at fixing the problem issuing a silent recall in response to an Office of Defects Investigation probe that went nowhere. The automaker implemented a customer service satisfaction campaign that began in 2007 and was extended in 2009 and 2010. Volkswagen consumers, however, are still complaining about burning seats. More than half were lodged with the agency from 2011 to the present.

Most recent complaint came into the agency this month:

I own a 2000 VW Jetta. My son and I were heading home after a college visit, he turned on his seat heater and began to nap. 20 minutes later, he popped up rubbing his shoulder, the seat heater caused the seat to catch fire and burned a portion of the seat, his shirt and shoulder. I called the dealer and was told they've never heard of that issue and that there has never been a recall for such an issue. I then did an internet search and found where it's a very common issue.

Jeep has issued two seat heater recalls in 2006 and 2009, but for the same group of vehicles, 102,354 Jeep Grand Cherokees. Unfortunately, Jeep owners from the 2002-2004 model years continued to complain, most recently in July:

Seat heaters have been getting progressively hotter. Passenger side got so hot I thought I was burned. My husband and I heard a pop on passenger side and seat heater slowly cooled down and now does not work. Driver side seat so hot we can't use it. I was talking to another Jeep owner and he said he experienced the same thing whereas his wife actually had red marks on her body for a few days. Why is there no recall?

Mercedes has neither mounted a recall, issued a TSB nor launched a customer satisfaction campaign. No, according to a recent class action filed in U.S. District Court in the Central District of California, Mercedes has taken the silent recall one step further, mounting a gag-order recall. The economic class action stems from a May 2014 incident, in which Elizabeth Callaway was driving her 2006 Benz with a friend and the seat heaters. Both smelled smoke, but San Diego County was plagued by brush and wildfires at the time, so both passed the smell off to events outside of the car. The next day, Callaway turned on her seat heater, and again, smelled smoke. But this time, the smoke was definitely inside the vehicle. She rolled down her windows to air the car out, and when she arrived home five minutes later, there was a pain on her left size, a hole through her dress and a corresponding hole through the leather upholstery and seat padding.  

Mercedes agreed to fix her driver’s side seat heater only if she signed a release, agreeing to accept a $500 payment, surrender all claims related to seat heaters against the manufacturer and keep the whole thing confidential. Mrs. Callaway declined.

As The Safety Record pointed out in October, it is likely based on the 17 property damage EWR complaints that Mercedes has submitted to the agency over a decade, that the automaker has been under-reporting property-damage EWRs (see Elective Warning Reports Redux). And, based on the frequency of VOQs regarding seat heaters submitted by Mercedes owners, we suggested that some of those unreported property damage EWRs probably concerned seat heater burns. The December lawsuit also notes that “Mercedes Benz USA has concealed the extent of the issue from NHTSA by not filing all of its Early Warning Reporting claims regarding failed seat heaters.”

Why Isn’t Burning Occupants A Safety Hazard?

Back in the day, NHTSA thought interior car fires were quite undesirable. It was so long ago, that the agency was called the National Highway Safety Bureau. And, in 1968, when bureau representatives met with automakers and the fabric industry to hammer out an interior flammability standard, Mr. Joseph F. Zemaitis, from the Office of Standards on Post Crash Standards explained its purpose:   

The material must be sufficiently resistant to burning so that if ignition does start, the driver and the occupants would have enough time to stop the car and get out. But you can imagine some of the conditions under which that would be quite difficult. For example, a dropped cigarette or let us say a dropped lighter, and we have a number of instances of dropped lighters that did not close but kept on burning, both liquid fuel and gas butane fuel, let's imagine that happens on a six lane Los Angeles highway, the traffic is moving at 65 miles per hour and we’re going to be getting into another increasing area of such possibilities. Not only is the thing dangerous to the occupants but to those involved in a panic it might result in many, many cars being involved in the crashes. We have on record of instances of fires that took place so rapidly in a moving car that there have been fatalities and very serious injuries before the car could be stopped and the occupants removed. So we do know that there are at least some conditions where materials are used of such a nature that extreme danger is involved. The probability that this will always happen with a dangerous material may be remote. But we are interested in, nevertheless, setting a standard so that all materials are adequately evaluated by methods that are common to everybody in the industry so there is complete understanding as to how they will be tested and where they can be tested and, how they will be used so that we eliminate this potential hazard not only now but for the future to come.

Federal Motor Vehicle Safety Standard 302, published in 1971 states: “The purpose of this standard is to reduce the deaths and injuries to motor vehicle occupants caused by vehicle fires, especially those originating in the interior of the vehicle from sources such as matches or cigarettes.”

Mr. Zemaitis and company did not anticipate that 40 years hence, fewer people would smoke, but in the future that came, automobile seats had taken up the habit and the danger would come from what lay under the upholstery. And all that hysterical talk about the beginnings of an interior car fire on a six-lane LA highway – you can imagine it happening on a mountain road in Aspen, or on your way home from a college visit. You can imagine putting the fire out with snow like this driver:

I was in my 2007 Mercedes GL450 and had driven approx. 2 miles with my front driver's seat heater on. I started to notice a strange smell and suddenly the cabin was starting to fill up with smoke. I immediately stopped the vehicle and discovered the left side of the back of my front driver’s seat was on fire. Snow was on the ground so I scooped up snow to pack in the fire/hot spot which had burned a large hole through the vinyl and inside padding material. I later noticed that my jacket had burn marks and a hole in the exact location of the point of the fire.

What consumers and The Safety Record could not have imagined was NHTSA now thinks these scenarios are no big deal. Since 2000, there have been six seat heater investigations: 2 for Volkswagen, 2 for Chrysler and 2 for Mercedes. But all of them ended with no agency action. And if one reads the Closing Resumes, one gets the distinct impression that ODI thinks that people who complain about seat heater burns and fires to be serial exaggerators – about the nature of the event and the extent of their injuries.

The Closing Resume of Engineering Analysis 04-010 concerning seat heater malfunctions in 2002-2003 Volkswagen Jettas is one such example. The agency and the manufacturer had 290 complaints; 593 warranty claims; 77 injuries and 134 fires. Yet, the agency concluded that: “such failures do not pose a significant risk of injury or fire. ODI believes that further investigation would not likely identify a safety-related defect trend.” (Obviously, this pre-dates the Friedman Engineering Defect Universal Protocol [FEDUP], which states: one is an anomaly; two is a trend.) The final report takes pains to dismiss the belly-aching of consumers who thought that the seat heater should not get hot enough to burn holes through the seat:

Only one of these complaints alleged that "flames" were present, and three consumers reported having sought medical attention for their bum injuries. Seventy-seven of the consumer complaints indicated that their clothing had sustained burn damage. ODI found that the allegation of fire were found consistently to refer to visible and localized heat damage to the fabric of the seat cover, as opposed to the occurrence of flames.

So a smoldering cigarette on a car seat is an occasion for rulemaking, but a smoldering heater in a car seat is an opportunity for the agency to opine that people who can afford vehicles with seat heaters are a bunch of privileged babies.

When it took up the issue Safety Research & Strategies argued that regardless of the volume of complaints, seat heaters should never reach temperatures higher than the well-established limits of human tolerance – by design or defect. Some can reach temperatures up to 150ºF in real-world testing, and produce severe burns within minutes of contact. Human heat tolerances have been long established; a maximum temperature limit is a design concept that has been recognized and incorporated by other consumer products manufacturers. There is no reason why the auto industry can’t do likewise. But, apparently there is still little motivation to do so.

Some in the industry appear to get it. Aston Martin, in its Part 573 Chronology of the defect, explained the problem and the solution with little fuss:

“A Recall Committee convened on November 18, 2014 and determined that:

  • A potential defect could occur in the relevant vehicle population,
  • That this defect could lead to a potential safety risk, and,
  • That a voluntary safety recall be completed.”

That’s how it’s done. 

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