I'm Neal and I am here to assist you. Only accept when you are happy with my assistance. If I can't help I will open your Question to other experts.
Are you having any symptoms? Have the codes been cleared oonly to have them return? It is going to take a diagnostic to determine the cause.
Here are the possible causes for P0731, the P0876 is likely just a symptom of the P0731
It might just be a solenoid issue which is common on those, but it will take a diagnostic to know.