A method of using a radio frequency sensor for determining an estimate of soot load in a diesel particulate filter is disclosed, The method comprises: receiving a first mean attenuation value derived from attenuation values for each of a first plurality of radio frequencies within a first band of radio frequencies detected by the radio frequency sensor; and receiving first standard deviation data for the mean attenuation value relating to the first plurality of radio frequencies within the first band of radio frequencies. The method further comprises: determining whether the standard deviation data exceeds a standard deviation threshold, In the event that the standard deviation data does not exceed a standard deviation threshold, the method uses the first mean attenuation value to infer a value for soot load in the diesel particulate filter, in the event that the standard deviation data exceeds a standard deviation threshold, the method comprises: receiving a second mean attenuation value derived from attenuation values for each of a second plurality of radio frequencies within a. second band of radio frequencies; and receiving second standard deviation data relating to the mean attenuation value for a second plurality of radio frequencies within the second band of radio frequencies detected by the radio frequency sensor, In the event that the second standard deviation data does not exceed the standard deviation threshold, the method uses the second mean attenuation value to infer the value for soot load in the diesel particulate filter.

A method of ageing a component of an exhaust gas after-treatment system including the steps of combusting fuel to subject the component to a continuous thermal ageing and simultaneously target loading at least certain sections of the component with ash. The method can be used on a test bench.

A method, system, and apparatus relating to operating an internal combustion engine include steps or features for determining a performance threshold of a particulate filter disposed in an exhaust gas flow of the engine having a set time interval between regeneration events of the particulate filter; determining a rate at which the particulate filter is reaching the performance threshold; and controlling an exhaust gas characteristic to control the rate so that the performance threshold is reached at or just before an end of the time interval. In an embodiment, there are steps or features for interpreting a filter condition of the particulate filter; determining a particulate matter load rate of the filter as a function of the condition; determining a limit of an exhaust gas characteristic based on the load rate; and controlling engine operation to control the exhaust gas characteristic to satisfy the limit.

Methods and/or systems for operating an exhaust-gas aftertreatment system of an internal combustion engine include: setting the internal combustion engine to a diagnostic operating mode with relevant diagnostic operating parameters of the internal combustion engine are set to correspond with diagnostic default values; inducing a targeted, defined NH.sub.3 and/or NO.sub.X concentration change upstream of the filter; measuring the NH.sub.3 and/or NO.sub.X concentration change downstream of the filter; providing a correlating concentration comparison value; evaluating the concentration change on the basis of the respective concentration comparison value and predefined limit values; and diagnosing the SCR particle filter as defective if the evaluation yields that the concentration comparison value has overshot a predefined limit value.

A method for the operation of a particulate filter in an exhaust aftertreatment system of a combustion engine (200) with the following steps: set up (111, 116) a pressure difference model, which models a measured pressure difference (Δp) which drops across the particulate filter (210) as a function (220) of a volume flow ({dot over (V)}) through the particulate filter (210) with an offset value (a.sub.0, C); measure (120) multiple measurement values (245) for the pressure difference (Δp) at different volume flows ({dot over (V)}) and solve (130) the pressure difference model as a function of the pressure difference (Δp), whereby the offset value (a.sub.0, C) is also determined.

Systems and methods are described for performing a diagnostic on an exhaust gas aftertreatment system. A gas entry parameter into a portion of an exhaust system of an engine is determined. In response to determining that the gas entry parameter is less than the predetermined threshold, a level of NH3 in the exhaust gas is determined. In response to determining that the level of NH3 is above a threshold value, degradation of a particulate filter of the exhaust gas aftertreatment system is indicated.

A method (200) for determining an amount of hydrocarbons in an exhaust gas (10) downstream of a lean-operation internal-combustion engine (110), comprising the following steps: observing a first catalyst heating mode of the internal-combustion engine (110) at a high catalyst temperature, wherein a predefinable amount of fuel having a predominantly non-combusting portion is introduced into a combustion chamber of the internal-combustion engine (110); determining an actual temperature change downstream of an oxidation catalyst (120) downstream of the internal-combustion engine (110) during the first catalyst heating mode; and determining the amount of hydrocarbons (cHC) in the exhaust gas (10) upstream of the oxidation catalyst (120) based on the actual temperature change. Furthermore, a computing unit (140) and a computer program for carrying out such a method (200) are proposed.

A gasoline particulate filter (GPF) diagnostic technique utilizes an upstream temperature sensor arranged at an upstream point relative to a GPF brick that the GPF is configured to house and configured to measure an upstream temperature of exhaust gas produced by an engine, a downstream temperature sensor arranged at a downstream point relative to the GPF brick and configured to measure a downstream temperature of the exhaust gas produced by the engine, and a controller configured to detect whether the GPF brick is damaged or missing based on a temperature difference between the upstream and downstream exhaust gas temperatures, a set of temperature thresholds, and a current operational mode of the engine.

Methods and systems are provided for monitoring a change in exhaust particulate filter (PF) soot load during an engine non-combusting condition. In one example, a method may include, responsive to a higher than threshold PF temperature immediately prior to an engine shutdown, estimating a rate of soot burn when the engine is no longer combusting, and estimating a soot load on the PF during and at an onset of immediately subsequent engine start based in part on the rate of soot burn.

A particulate matter sensor includes a sensor element that includes a measurement member and a heater. An anomaly determiner performs determination that there is a break fault in a signal path of the measurement signal in response to both: (1) A first determiner, which determines whether a first measurement value of the measurement signal is higher than or equal to a predetermined normal determination threshold while the measurement voltage is applied between the measurement electrodes and the temperature of the measurement member is controlled at a first determination temperature, making a negative determination; and (2) A second determiner, which performs negative determination while the measurement voltage is applied between the measurement electrodes and the temperature of the measurement member is controlled within a predetermined temperature range that is higher than the first determination temperature and lower than a second determination temperature, making a negative determination.