The Cummins CM850 Engine Control Module was used in 2003-2007 Cummins ISB, ISC, and ISL diesel engines to manage fuel injection, emissions systems, and diagnostics. The CM850 ECM is responsible for engine performance, providing real-time adjustments to operating conditions. Its robust design and proven track record make it a trusted component in commercial trucking applications. Weller Truck Parts offers professionally remanufactured Cummins CM850 ECMs that exceed OEM standards for quality and performance. Each ECM is carefully disassembled, inspected, and remanufactured by IPC certified technicians in Michigan, USA. Weller's time tested reman philosophy is to replace all high current, high duty cycle, and active components, regardless of core condition. We do not simply replace the failed part, or combine multiple cores to make one good working unit, our reman electronics perform comparable to OE new. Weller’s remanufactured ECMs are backed by an industry-leading warranty, and customers benefit from Weller’s knowledgeable tech support and responsive customer service. Whether you're replacing a failed module or proactively maintaining your fleet, Weller delivers dependable solutions with the support you need to keep your trucks running strong. Interchanges to: 3954430, 3965159, 4921776