Abstract: A method of detecting urea-derived deposits in the exhaust line of an internal combustion engine having an SCR (selective catalyst reduction) aftertreatment system. A radio frequency (RF) transmitter is placed upstream of the SCR system's urea injector, and an RF receiver is placed downstream of the mixer. The transmitter and receiver are used to acquire baseline RF data representing a clean condition exhaust line without deposits. During subsequent operation of the engine, the transmitter and receiver are used to acquire subsequent RF data, which is compared to the baseline data after being corrected for temperature differences. If the comparison indicates the presence of one or more deposits, an alert signal is generated.

Abstract: A method of detecting urea-derived deposits in the exhaust line of an internal combustion engine having an SCR (selective catalyst reduction) aftertreatment system. A radio frequency (RF) transmitter is placed upstream of the SCR system's urea injector, and an RF receiver is placed downstream of the mixer. The transmitter and receiver are used to acquire baseline RF data representing a clean condition exhaust line without deposits. During subsequent operation of the engine, the transmitter and receiver are used to acquire subsequent RF data, which is compared to the baseline data after being corrected for temperature differences. If the comparison indicates the presence of one or more deposits, an alert signal is generated.