× Auto Repair Pros Member Benefits TechHelp Knowledge Base Forums Resources My iATN Marketplace Chat Pricing About Us Join Industry Sponsors Video Members Only Repair Shops Auto Pro Careers Auto Pro Reviews
Join Now
International Automotive Technicians Network
Re: Isuzu NPR/NQR P0420
Posted to HD/Fleet Forum on 5/11/2018

Check the exhaust brake for proper operation . Also inspect the 5th injector and bore that it is in. It tends to be clogged. In the city please verify everything else is operating correctly. Air filter, turbo, injectors etc.... Login to read more.