Method for operating an exhaust gas post-treatment device for an internal combustion engine of a motor vehicle, in particular of a motor car

A method for operating an exhaust gas post-treatment device for an internal combustion engine of a motor vehicle, wherein exhaust gas from the internal combustion engine flows through the exhaust gas post-treatment device, and wherein the exhaust gas post-treatment device comprises:

• an oxidation catalyst with a first catalytic coating, a first heating element disposed upstream of the oxidation catalyst or with the first catalytic coating and configured to heat the exhaust gas and/or the oxidation catalyst at a first heating point, a dosing element configured to introduce a reducing agent is into the exhaust gas at an introduction point downstream of the oxidation catalyst and the first heating point, and an SCR system having a first SCR catalyst disposed downstream of the introduction point, the method comprising:
• determining:
• that a temperature downstream of the first heating point and a temperature of the SCR system are below respective target temperatures, that component protection temperatures are not exceeded, and that a minimum temperature of the internal combustion engine for carrying out a post-injection has been reached or exceeded;
• calculating a temperature rise by which the temperature of the SCR system is to be increased such that the temperature of the SCR system reaches its respective target temperature;
• determining whether the temperature rise can be achieved within a pre-determined duration by the first heating element without carrying out the post-injection;
• in response to determining that the temperature rise can be achieved within the pre-determined duration by the first heating element without carrying out the post-injection, then the exhaust gas, and thus the SCR system, via the first heating element, without carrying out the post-injection;
• and
• in response to determining that the temperature rise cannot be achieved within the pre-determined duration by the first heating element without carrying out the post-injection, heating the exhaust gas, and thus the SCR system, via the first heating element and by carrying out the post-injection.