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The National Highway Traffic Safety Administration and Mercedes-Benz are advising owners of the 2006-2012 model years of the ML-, GL-, and R-Class (gallery below) not to drive the models until a recall repair is complete. This campaign affects 292,287 vehicles in the United States. Mercedes knows of no crashes, injuries, or deaths from this problem.

"We are advising affected customers to stop driving their vehicles. MBUSA will also offer complimentary towing to owners of affected vehicles to attend the workshop," Mercedes said in a statement that a spokesperson from the automaker sent to Motor1.com.

Gallery: Mercedes-Benz R-Class In Depth

These vehicles may have corroded brake boosters that could severely affect their braking ability. It's also possible for the booster to leak, resulting in more force being necessary on the pedal to slow the affected vehicles. 

In particularly severe cases, hard stopping could damage the booster and cause the brake pedal to stop working entirely. 

NHTSA's statement indicates that signs of a vehicle with a corroded brake booster include the brake pedal might have a different feeling than normal. Another indicator is a hissing or airflow noise when applying the brakes.

To solve the issue, Mercedes will inspect the affected vehicles. According to its filing with NHTSA:

"Vehicles that show advanced corrosion will have an additional test performed to ensure the functionality of the brake booster. Vehicles that pass the additional test may be driven for up to two years but must return for an additional repair."

If a model doesn't pass the additional test, Mercedes will replace the brake booster. If the parts aren't immediately available, the dealer will arrange for alternate transportation for the customer.

According to the chronology that Mercedes submitted to NHTSA, the automaker began investigating this problem in July 2021 after it received a report from outside of the United States of a customer who experienced reduced braking support. There were no injuries or damage in that case, and Mercedes requested parts from that vehicle for further analysis. The company found corrosion to the brake booster housing.

In September 2021, Mercedes began a field study to figure out the scope of this problem. In November, it also began research to figure out the cause of the corrosion issue. By March 2022, the automaker was only able to find one case in the United States where a corroded brake boost caused poor stopping performance. On May 2, 2022, the company decided there was a potential safety risk and decided to conduct a recall.

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