thereb - 11/1/2025 19:32 If you have a Maxxforce engine, it has two separate coolant temp sensors. ECT1 is the main temp sensor and the sensor used for your gauge. ECT2 is basically for the egr cooler systems. If you have a Maxxforce 13, it uses a separate coolant control valve to direct coolant through its own separate radiator. Probably have a failed valve and coolant isn't flowing through and over heating. Edit: I saw this post referencing this code on another forum and thought it might help.