How to Fix a Noisy Mercedes Catalytic Converter

1. Check the warranty. Your Mercedes may not be covered by the federally mandated Environmental Protection Agency warranty. Federal law emissions warranty specifies that if your car was manufactured before 1996, the catalytic converter is still under warranty only if the car has less than 50,000 miles on it. If the car was manufactured after 1996, the car is legally required to have more than 80,000 miles on it or be more than eight years old to be out of warranty.Some Mercedes vehicles have documented issues with the catalytic converters. Mercedes reached a settlement with the EPA to extend the emissions warranties on these vehicles.
2. Take your Mercedes to the dealership, or a mechanic who regularly handles these cars, and have the catalytic converter tested. You will need to go to a mechanic who is familiar with the car's exhaust system requirements and has access to original equipment manufacturer, or OEM, exhaust parts. The converter used to replace your Mercedes converter must be identical to the original Mercedes catalytic converter.If your car is still covered by the federal warranty, it will need to be taken to the Mercedes dealership.
3. Have the mechanic thoroughly document the problem with the converter, then, if necessary, replace it with an identical new converter. Documentation of the problem is a legal requirement if the converter needs to be replaced.Since tampering with converters is illegal, your noisy converter will probably be replaced. If the converter is still functioning, the mechanic is not legally allowed to remove it.
4. Make sure the mechanic also fills out a warranty card as required by federal law. Save a copy of everything for your records in case of emissions inspection problems at a later date.