We would first preform an inspection on the EGR cooler to confirm we are able to clean it. Some types of EGR coolers we cannot clean. Our process includes soaking the EGR Cooler with a cleaning solution over night. We would then flush the cleaning solution with water the next day and determine if it is good to go or if it will be soaked again. Depending on how dirty your EGR Cooler is it could potentially need to soak in the solution 1-3 times for best results.