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 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: 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: An exhaust diagnostic system includes a selective catalyst reduction (SCR) efficiency testing module that determines an efficiency of a SCR catalyst. An exhaust gas temperature management module selectively adjusts a temperature of the SCR catalyst to a predetermined temperature range using intrusive exhaust gas temperature management. A test enabling module initiates an SCR efficiency test using the SCR efficiency module after failing a prior SCR efficiency test and while the temperature of the SCR catalyst is within the predetermined temperature range.

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 glow plug control system for a vehicle comprises a mode control module and a fault diagnostic module. The mode control module enables one of a first mode and a second mode of operation based on a period of time that a glow plug is ON during a drive cycle. The fault diagnostic module selectively diagnoses a fault based on a first message, a second message, and a third message when the first mode is enabled and selectively diagnoses the fault independent of the second and third messages when the second mode is enabled.

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: An exhaust diagnostic system includes a selective catalyst reduction (SCR) efficiency testing module that determines an efficiency of a SCR catalyst. An exhaust gas temperature management module selectively adjusts a temperature of the SCR catalyst to a predetermined temperature range using intrusive exhaust gas temperature management. A test enabling module initiates an SCR efficiency test using the SCR efficiency module after failing a prior SCR efficiency test and while the temperature of the SCR catalyst is within the predetermined temperature range.

Abstract: A glow plug control system for a vehicle comprises a mode control module and a fault diagnostic module. The mode control module enables one of a first mode and a second mode of operation based on a period of time that a glow plug is ON during a drive cycle. The fault diagnostic module selectively diagnoses a fault based on a first message, a second message, and a third message when the first mode is enabled and selectively diagnoses the fault independent of the second and third messages when the second mode is enabled.