Abstract: A vehicle includes an engine, an exhaust system, a selective catalytic reduction (SCR) device, a first and a second NOx sensor configured to respectively measure an upstream and a downstream NOx level, and a controller or host machine. The controller, via the present method, calculates a NOx conversion efficiency rate of the SCR device using the NOx levels from the sensors. At the end of a key cycle when an accumulated amount of upstream NOx is less than a calibrated upstream NOx level, the controller determines if the NOx conversion efficiency rate is presently passing or failing. The accumulated upstream NOx is recorded in memory for use in calculating the NOx conversion efficiency rate during a subsequent key cycle only when the NOx conversion efficiency rate is presently passing at the end of the key cycle. A control system for the vehicle uses the controller and sensors as noted above.

Abstract: A diagnostic system of a vehicle includes an impedance module and a diagnostic module. The impedance module determines an impedance of a sensing element of an exhaust gas oxygen sensor based on a response of the sensing element to a change in current through the sensing element. The diagnostic module selectively diagnoses a fault associated with the exhaust gas oxygen sensor based on the impedance of the sensing element.

Abstract: A system includes a pump control module and a pump diagnostic module. The pump control module switches a switchable water pump from off to on. The pump diagnostic module diagnoses a fault in the switchable water pump based on a first difference between an engine material temperature and an engine coolant temperature when the switchable water pump is switched from off to on. The engine coolant temperature is a temperature of coolant circulated through an engine and the engine material temperature is a temperature of at least one of an engine block and a cylinder head.

Abstract: A reductant injector is configured to dispense a reductant into an exhaust gas feedstream of an internal combustion engine upstream of a selective catalytic reduction device. The reductant injector of a reductant injection system is monitored by generating injector pulsewidth commands corresponding to a prescribed reductant flowrate, monitoring the injector pulsewidth commands, verifying the prescribed reductant flowrate corresponds to the injector pulsewidth commands, monitoring a fluidic pressure in the reductant injection system, estimating a first injected quantity of the reductant corresponding to the injector pulsewidth commands, estimating a second injected quantity of the reductant corresponding to the fluidic pressure in the reductant injection system, and comparing the first and second injected quantities of reductant.

Abstract: A system according to the principles of the present disclosure includes a pump control module, an actuator control module, and a torque reserve module. The pump control module switches a water pump between on and off. The water pump circulates coolant through an engine when the water pump is on. The actuator control module controls a first actuator of the engine based on a first torque request and that controls a second actuator of the engine based on a second torque request. The torque reserve module adjusts a torque reserve before the water pump is switched on or off based on a change in engine load expected when the water pump is switched on or off.

Abstract: A diagnostic system for a vehicle includes an error module, an equivalence ratio (EQR) module, a threshold determination module, and a fault indication module. The error module determines an error value based on a difference between an amount of oxygen in exhaust measured by an exhaust gas oxygen sensor (EGO) upstream of a catalyst and an expected value of the amount. The EQR module selectively controls fuel injection based on the error value. The threshold determination module determines an error threshold based on a flow rate of fuel vapor from a vapor canister to an intake manifold of an engine. The fault indication module selectively indicates that a fault is present in the EGO sensor based on the error value and the error threshold.

Abstract: A system according to the principles of the present disclosure includes a pump control module and a pump diagnostic module. The pump control module commands a water pump to switch between on and off, wherein the water pump circulates coolant through an engine when the water pump switches on as commanded. The pump diagnostic module diagnoses a fault in the water pump based on a change in a crankshaft speed of the engine when the water pump is commanded to switch between on and off.

Abstract: A system according to the principles of the present disclosure includes an error count module and a sensor diagnostic module. The error count module increases an error count when an actual air/fuel ratio is different from a desired air/fuel ratio and selectively adjusts the error count based on an actual engine speed. An oxygen sensor generates a signal indicating the actual air/fuel ratio. The sensor diagnostic module diagnoses a fault in the oxygen sensor when the error count is greater than a first predetermined count.

Abstract: A diagnostic system for a vehicle includes a comparison module, a disabling module, and a fault indication module. The comparison module indicates whether a temperature of engine coolant is less than a first predetermined temperature. The disabling module disables the comparison module until the temperature of the engine coolant is greater than a second predetermined temperature. The fault indication module diagnoses a fault in response to the comparison module indicating that the temperature of the engine coolant is less than the first predetermined temperature.

Abstract: A method of assessing overall efficiency of a selective-catalytic-reduction catalyst includes monitoring instantaneous efficiency of the catalyst. The method also includes determining the overall efficiency by summing instantaneous efficiency values weighted by a first set of coefficients if the most recent instantaneous efficiency value is above an instantaneous efficiency threshold. The method additionally includes determining the overall efficiency by summing instantaneous efficiency values weighted by a second set of coefficients if the most recent instantaneous efficiency value is equal to or below the instantaneous efficiency threshold. Furthermore, the method includes determining whether the overall efficiency has dropped below an overall efficiency threshold and reporting when the overall efficiency has dropped below the overall efficiency threshold.

Abstract: An apparatus and method of controlling a vehicle aftertreatment system is provided. The aftertreatment system treats exhaust gas produced by the vehicle engine and includes a particulate filter, and a NOx reducing device such as a selective catalytic reduction (SCR) device. The particulate filter is configured to regenerate to remove accumulated particles when the exhaust gas is heated above a regeneration temperature. A diagnostic device is included for monitoring the aftertreatment system. The diagnostic device may be a sensor for measuring the oxides of nitrogen (NOx) and/or an SCR efficiency monitor. A controller is employed to optimize the function of the diagnostic device. The controller does not enable the diagnostic device when the vehicle is powered until one or more entry conditions are satisfied.

Abstract: An exhaust diagnostic control system comprises a test enabling module, an exhaust gas temperature management module, and an exhaust diagnostic control system. The test enabling module is configured for executing a process for depleting a reductant load and subsequently establishing a known concentration of reductant on an after-treatment component following an occurrence of one or more trigger events. The exhaust gas temperature management module is configured for selectively adjusting a temperature of the after-treatment component to a predetermined temperature range using intrusive exhaust gas temperature management. The component management module is configured for executing a NOx reduction efficiency test following completion of the process for depleting a reductant load and subsequently establishing a known concentration of reductant on the after-treatment component. The NOx reduction efficiency test comprises determining a NOx reduction efficiency associated with the after-treatment component.

Abstract: A control system for a selective catalytic reduction (SCR) system includes a conversion efficiency determination module, an ammonia slip determination module, and a diagnostic module. The conversion efficiency determination module determines a conversion efficiency of an SCR catalyst. The ammonia slip determination module determines an amount of ammonia slip across the SCR catalyst when the conversion efficiency is less than a predetermined threshold. The diagnostic module determines pass/fail statuses of a reductant supply and the SCR catalyst based on the amount of ammonia slip and at least one ammonia slip threshold.

Abstract: A monitoring module selectively generates a request to at least one of: transition from providing rich fueling an engine to operating the engine in a fuel cutoff (FCO) state; and transition from operating the engine in the FCO state to providing rich fueling to the engine. In response to a response to the request, the monitoring module: selectively controls fueling to the engine to perform the at least one of the transitions; and selectively determines whether a fault is present in a component based on a response to the at least one of the transitions. A hybrid control module controls an electric motor of the hybrid vehicle and that selectively generates the response.

Abstract: A system according to the principles of the present disclosure includes an error period module and a sensor diagnostic module. The error period module determines an error period based on an amount of time that a first air/fuel ratio and a desired air/fuel ratio are different. A first oxygen sensor generates a first signal indicating the first air/fuel ratio. The sensor diagnostic module diagnoses a fault in the first oxygen sensor when the error period is greater than a predetermined period.

Abstract: A system includes a pump control module and a pump diagnostic module. The pump control module switches a switchable water pump from off to on. The pump diagnostic module diagnoses a fault in the switchable water pump based on a first difference between an engine material temperature and an engine coolant temperature when the switchable water pump is switched from off to on. The engine coolant temperature is a temperature of coolant circulated through an engine and the engine material temperature is a temperature of at least one of an engine block and a cylinder head.

Abstract: An exhaust diagnostic system comprises a selective catalyst reduction (SCR) component testing module, an exhaust stream temperature management module, and a test enabling module. The component testing module executes an SCR component efficiency test. The exhaust stream temperature management module adjusts a temperature of the SCR component to a predetermined temperature range. The test enabling module executes a process for depleting a reductant load and subsequently initiates an SCR component efficiency test while the temperature of the SCR catalyst is within the predetermined temperature range. A method for diagnosing an exhaust system comprises determining an efficiency of an SCR component and selectively adjusting a temperature of the SCR component to a predetermined temperature range. The method also includes executing a process for depleting a reductant load and initiating an SCR component efficiency test while the temperature of the SCR component is within the predetermined temperature range.

Abstract: A diagnostic control module includes a temperature gradient module. The temperature gradient module determines a temperature gradient across a selective catalytic reduction (SCR) catalyst of an exhaust system of an engine based on a plurality of temperature signals. A calibration module determines a weighted average based on the plurality of temperature signals. A SCR efficiency control module disables conversion efficiency monitoring based on the temperature gradient and the weighted average.

Abstract: A system according to the principles of the present disclosure includes a diagnostic execution module and a diagnostic disabling module. The diagnostic execution module diagnoses a fault in at least one of an oxygen sensor and a catalytic converter based on input received from the oxygen sensor. The diagnostic disabling module disables the diagnosing based on at least one of a temperature of the catalytic converter and a mass flow rate of air flowing through the catalytic converter.

Abstract: A method to indicate an injector fault in a urea dosing module in an aftertreatment system includes monitoring a control command for the urea dosing module, determining a carry frequency for the control command, monitoring a delivery line pressure for the delivery line, evaluating the delivery line pressure at the carry frequency, and indicating the injector fault based upon the evaluating.