Tools for exhaust maintenance assist with repairs, cleaning or solving emission problems. Pipe expanders shape, expand, and remove dents in exhaust pipes to improve airflow. Oxygen sensor wrenches remove damaged air-quality parts to solve emission issues. Other commonly used exhaust tools include pipe and tubing cutters for removing broken or rusted exhaust pipes, hanger removal pliers to detach rubber supports from the exhaust system, and donut stretchers to hold mounting rubber rings in place.