WASHINGTON—The National Highway Traffic Safety Administration has denied the petition of Mercedes-Benz U.S.A. L.L.C. and its parent company, Daimler A.G., for a finding of inconsequential noncompliance in the case of faulty tire pressure monitoring systems in certain Mercedes-Benz vehicles.
The denial of the petition means that Mercedes must conduct a formal recall of the affected vehicles, observing all protocols for recalls set forth by NHTSA.
The vehicles involved were 4,769 Mercedes S-class cars, 221 platform, model years 2011 and 2012, which were manufactured between March and August 2011. Mercedes told NHTSA it has corrected the problem in all but 252 vehicles through a service campaign.
The TPMS malfunction indicators in the subject vehicles may not perform according to the requirements of federal law, Mercedes said.
According to the federal standard on TPMS, the malfunction lights must flash for 60 to 90 seconds to notify the driver, then remain continuously illuminated.
Mercedes said the cars in question instead display a steady vehicle symbol, along with the following four pieces of information:
• The actual tire pressure on each wheel with a sensor;
• Two blank dashes next to each wheel with faulty sensors or signals;
• The word “Service” at the bottom of the display; and
• A clear text message reading, “Wheel Sensor(s) Missing.”
The only instance in which motorists would encounter a problem, Mercedes said, was when they replaced the standard wheels with snow or custom tires—in which case they would already know the wheels with sensors had been removed.
Also, the malfunction indicators on the subject vehicles offer significantly more information than the indicators required by law, the auto maker said.
In denying Mercedes' petition, NHTSA said there may be cases in which a motorist doesn't know the TPMS sensors have been removed.
“For example, if the ignition were cycled by a second party after the sensors were removed and prior to the vehicle being returned to the owner, the owner may not see the first and only malfunction indication.
“The potential risk is that the vehicle can then be operated with a TPMS that appears to be functioning properly,” the agency said.
Mercedes also argued that warnings in owners' manuals will prevent owners from misusing TPMS sensors. NHTSA replied, however, that many motorists ignore their manuals, and also there is no guarantee that vehicle owners will even keep their manuals throughout the vehicle's service life.