What is one method not used to clean a DPF?

Physical scraping is not considered a method for cleaning a Diesel Particulate Filter (DPF) due to the risk of damaging the fragile filter structure. DPFs are designed to capture and retain soot and particulate matter from the exhaust gases, and they are typically made from ceramic or other materials that can be easily compromised by abrasive actions.

More acceptable methods for cleaning a DPF include techniques such as back-flushing with compressed air, which helps to dislodge soot without causing damage, and kinetic vibration, which can effectively shake loose accumulated particulates without risking the integrity of the filter. Removal is also a part of the cleaning process, but it refers to taking the DPF off the vehicle for maintenance rather than a cleansing method itself. Thus, physical scraping is not a viable option, making it the correct answer in this context.