| abstract |
An exhaust purification system adapted to mix a liquid reducing agent with air and carry out injection feeding of the mixture upstream of reduction catalyst (20) to thereby effect reduction purification of NOx contained in exhaust, wherein noting the correlation between factors, such as travel distance, fuel consumption, air consumption and driving time, and the amount of liquid reducing agent consumed, whether the condition of injection of liquid reducing agent is normal or abnormal is monitored through judging of whether or not the amount of liquid reducing agent consumed at given travel distance, given fuel consumption, given air consumption or given driving time falls within a given range. |