Patent ID: 9458754
Filing Date: 2016-10-04
CPC Classification: F01N,Y02A,Y02T

Claim Text:
1. A method for diagnosing a reductant delivery system having a reductant pump and a reductant doser, the method comprising: operating the reductant pump to urge the reductant to flow through the reductant delivery system at a first operating condition; sampling reductant pressure during operation of the reductant pump to urge the reductant to flow through the reductant delivery system at the first operating condition to determine a first pressure at which the reductant is pressurized within the reductant delivery system; operating the reductant pump to urge the reductant to flow through the reductant delivery system at a second operating condition different from the first operating condition; sampling reductant pressure during operation of the reductant pump to urge the reductant to flow through the reductant delivery system at the second operating condition to determine a second pressure at which the reductant is pressurized within the reductant delivery system; calculating a pressure differential between the first and second pressures to provide a first pressure differential; comparing the first pressure differential with a threshold pressure differential comprising an injector blockage threshold defining a pressure differential boundary between the reductant delivery system in an unblocked condition and the reductant delivery system with a blocked injector; comparing the first pressure differential with a second threshold pressure differential responsive to the first pressure differential being greater than or equal to the first threshold pressure differential, wherein the second threshold pressure differential comprises a line blockage threshold defining a pressure differential boundary between the reductant delivery system with a blocked injector and the reductant delivery system with a blocked line; responsive to the first pressure differential being greater than or equal to the line blockage threshold: outputting a performance status to a vehicle system based on the comparison of the second pressure differential with the second threshold pressure differential.