A control module and method for an exhaust system of an engine can include a secondary air intake (SAI) pressure module that monitors SAI pressure. An accumulation module can accumulate an SAI string length based on the monitored SAI pressure. A calculation module can determine an average SAI string length based on the accumulated SAI string length. A determination module can determine an operating characteristic of the vehicle exhaust based on the average SAI string length.
GM Global Technology
Mac Ewen, Ian J.; Hall, Martin L.; Murray, Lawrence O.; Grow, Julia C.; Van Camp, Richard; Prout, David Edward; and Anilovich, Igor, "Algorithm to Diagnose Leaks or Blockages Downstream of the Secondary Air Injection Reaction (SAIR) Pressure Sensor" (2009). Physics Patents. 3.