We unpluged a catalytic converter on this Mercedes Benz that was completely plugged up. Undo the exhaust on the bottom of the converter and plug it with a plastic plug then undo the upper O2 sensor and fill the converter with Klean Striip Concrete & Metal Prep over night and in the morning rinse it out with a water hose. We started the engine after that and the check engine for the DPF filter went out.
