What is the impact of carbon buildup on drivability and performance?

One of the more common symptoms is a lack of power, especially when driving at higher speeds. Other symptoms could include cold stalling and cold-start difficulties, including rough running. In some cases, carbon buildup may cause one or more cylinder misfire codes (P030X) that will result in fuel inefficiency and poor performance. There is also a possibility of a failed NOX emission test and/or excessive ping on acceleration.