Patent ID: 9708953
Date: 2017-07-18
CPC Classifications: F01N,F02M,Y02A,Y02T

Claim:
1. A method for monitoring an oxidation catalyst in a vehicle exhaust system comprising: providing a diesel internal combustion engine (ICE) with an exhaust system, the exhaust system having an exhaust gas recirculation (EGR), a diesel oxidation catalyst/a diesel particulate filter (DOC/DPF) downstream from the EGR, a selective catalytic reduction (SCR) catalyst downstream of the DOC/DPF, a reducing agent dosing system operable to inject a reducing agent into the exhaust system upstream of the SCR catalyst, a first NOx sensor located upstream of the DOC/DPF and a second NOX sensor located downstream of the SCR catalyst; operating the diesel ICE with exhaust gas from the diesel ICE flowing through the exhaust system; executing a monitoring cycle, the monitoring cycle including: sending an alert signal that an efficiency of the DOC/DPF is decreasing if the at least one of the difference and the ratio between the first NOx sensor readings and the second NOx sensor readings is less than a predetermined reference value.