Method and an arrangement for monitoring the functioning of a sensor or an exhaust gas aftertreatment system

A monitoring arrangement for monitoring the functioning of an exhaust gas aftertreatment system of a motor vehicle based on measuring values from a sensor as to the magnitude of a parameter related to exhaust gases flowing out of an exhaust gas aftertreatment appliance included in the exhaust gas aftertreatment system, wherein:

• the monitoring arrangement comprises
• calculation apparatus for calculating the magnitude of said parameter on the basis of a calculation model;
• and
• a processor arranged and operable to receive information from the sensor as to the measured magnitude of the parameter and information from the calculation apparatus as to the calculated magnitude of the parameter, the processor being operable:
• a) to establish a first comparison value (C1) based on the information from the sensor as to the measured magnitude of the parameter,
• b) to establish a second comparison value (C2) corresponding to the first comparison value (C1) based on the information from the calculation apparatus as to the calculated magnitude of the parameter,
• c) to establish a difference value (Vdiff) representing the difference between said comparison values (C1, C2),
• d) to repeat steps a)-c) during a period of time and establish a variance value (Vvar) representing the variance of the difference value (Vdiff) during this period of time, and
• e) to compare the variance value (Vvar) with a given threshold value (Vth) and generate information regarding the functioning of the exhaust gas aftertreatment system.

A computer program loadable into the internal memory of a computer in a motor vehicle wherein the vehicle comprises an exhaust gas aftertreatment system and a sensor for measuring the magnitude of a parameter related to exhaust gases flowing out of an exhaust gas aftertreatment appliance included in the exhaust gas aftertreatment system, the computer program comprising computer program code for causing the computer:

• a) to receive information from said sensor as to the measured magnitude of said parameter and establish a first comparison value (C1) based on said information;
• b) to calculate, on the basis of a calculation model, a value representing the magnitude of said parameter or receive information about said value calculated on the basis of a calculation model, and to establish a second comparison value (C2) corresponding to the first comparison value (C1) based on this calculated value;
• c) to establish a difference value (Vdiff) representing the difference between said comparison values (C1, C2);
• d) to repeat steps a)-c) during a period of time and establish a variance value (Vvar) representing the variance of a difference value (Vdiff) during this period of time;
• and
• e) to compare the variance value (Vvar) with a given threshold value (Vth) and generating information regarding the functioning of the sensor or the exhaust gas aftertreatment system.

A method for monitoring the functioning of a sensor arranged to measure the magnitude of a parameter related to exhaust gases flowing out of an exhaust gas aftertreatment appliance included in an exhaust gas aftertreatment system of a motor vehicle, the method comprising the steps of:

• a) establishing a first comparison value (C1) based on a measuring value from the sensor as to the magnitude of said parameter;
• b) establishing a second comparison value (C2) corresponding to the first comparison value (C1) based on a value of the magnitude of said parameter calculated by means of a calculation model;
• c) establishing a difference value (Vdiff) representing the difference between said comparison values (C1, C2);
• d) repeating steps a)-c) during a period of time and establishing a variance value (Vvar) representing the variance of the difference value (Vdiff) during the period of time;
• and
• e) comparing the variance value (Vvar) with a given threshold value (Vth) for causing generation of information regarding the functioning of the sensor (11).

A method for monitoring the functioning of an exhaust gas aftertreatment system of a motor vehicle based on measuring values from a sensor as to the magnitude of a parameter related to exhaust gases flowing out of an exhaust gas aftertreatment appliance included in the exhaust gas aftertreatment system,

• the method comprising the steps of:
• a) establishing a first comparison value (C1) based on a measuring value from the sensor as to the magnitude of said parameter;
• b) establishing a second comparison value (C2) corresponding to the first comparison value (C1) based on a value of the magnitude of said parameter calculated by means of a calculation model;
• c) establishing a difference value (Vdiff) representing the difference between said comparison values (C1, C2);
• d) repeating steps a)-c) during a period of time and establishing a variance value (Vvar) representing the variance of the difference value (Vdiff) during the period of time;
• and
• e) comparing the variance value (Vvar) with a given threshold value (Vth) for causing generation of information regarding the functioning of the exhaust gas aftertreatment system.