A diagnostic cold start emissions control system for an internal combustion engine includes a control module having a calculated engine-out energy module, an engine-out energy residual module, and a diagnostic system evaluation module. The calculated engine-out energy module is in communication with the engine-out energy residual module and is configured to determine an operating engine-out energy flow based on an operating engine torque. The engine-out energy residual module is in communication with the diagnostic system evaluation module and is configured to determine an engine-out energy residual based on the determined engine-out energy flow and an expected engine-out energy flow. The diagnostic system evaluation module is configured to determine whether the determined engine-out energy residual meets a predetermined value indicative of proper cold start emissions control.