What Are the Symptoms of a Dirty Throttle Body?

The symptoms of a dirty throttle body include rough idle, poor gas mileage, faulty CEL codes, stalling and poor acceleration. Poor gas mileage is the result of the vehicle's ECU, or computer, attempting to adjust the fuel mixture to compensate for throttle plates that are incapable of closing properly. Faulty CEL codes cause various sensor-related issues, such as an illuminated check engine light.