This diagnosis manual covers Kubota engines, specifically models V2607-CR-E4B, V2607-CR-TE4B, V2607-CR-TIE4B (DOC only), V3307-CR-TE4B, and V3307-CR-TIE4B (DOC only). These diesel engines feature a Common Rail System and Direct Injection fuel system, with emission controls meeting E4B, TE4B, and TIE4B standards, utilizing a Diesel Oxidation Catalyst. The V2607 offers a 2.6 L displacement, while the V3307 provides 3.3 L. Turbocharger options are available for TE4B and TIE4B variants. These engines are engineered for robust performance and reliability in various applications. This English-language diagnosis manual provides essential technical information for troubleshooting and understanding the operation of the specified Kubota engines. It details diagnostic procedures, system explanations, and troubleshooting charts to assist technicians and owners in identifying and resolving potential issues. While specific maintenance intervals, lubrication capacities, and filter replacement procedures are to be found in the vehicle's service manual, this document focuses on the diagnostic aspects crucial for maintaining optimal engine performance and longevity.