Patent ID: 8209964

Claim:
An exhaust control system for a combustion engine having a reduction catalyst, a reductant injector located upstream of the reduction catalyst, and a supply of reductant, the reduction catalyst includes a catalyst substrate, the exhaust control system comprising: a first sensor located upstream of the reduction catalyst to generate a first signal indicative of an amount of a constituent within the exhaust entering the reduction catalyst; a second sensor located downstream of the reduction catalyst to generate a second signal indicative of an amount of the constituent remaining within the exhaust exiting the reduction catalyst; a third sensor associated with the supply of reductant to generate a third signal indicative of an amount of reductant within the supply; and a controller in communication with the first sensor, the second sensor, and the third sensor, the controller being configured to: determine a change in an efficiency of the reduction catalyst based on the first and second signals; diagnose the change in efficiency based on the third signal by determining that a fluid added to the supply during a fill event has an improper solution when the change in efficiency corresponds to a fill event of the supply and is less than a first amount; verify the improper solution; and adjust future reductant dosing of the catalyst substrate by the reductant injector based on the verification in response to the diagnosis.