An engine control system includes a temperature determination module, a reducing agent control module, and a control module. The temperature determination module determines a temperature of a reducing agent injector heated by an exhaust gas. The reducing agent control module actuates the reducing agent injector to inject an amount of reducing agent into the exhaust gas when the temperature is greater than or equal to a temperature threshold. The control module controls a concentration of nitrogen oxides in the exhaust gas based on the amount of reducing agent injected into the exhaust gas.