SPN 520349 FMI 14

Usual cause is filters full of ash. Time for (2) new DPF"s. Make sure you remove soot sensor and clean with mineral spirits. Do a regen with laptop when done and reset ash accumulator.

 

Here's a link for that code.
4jciss.pdf (catbox.moe)

 

Because the sensor is not the problem, only a symptom. Carefully read the procedures for the code. Make sure there are no other codes, if so repair those first. The procedures and QualityTruck in this thread both tell you that there is too much ash in the DPF. Needs to be cleaned or replaced. Does not matter that they were replaced in Oct 2021. Upstream issues will cause issues in the aftertreatment area. Should have the intercooler and piping/connections and exhaust smoke or pressure tested for leaks. You really need the data such as exhaust temp before the DPF and after etc. to see what is going on, if anything is not right. If you don't get to the root of the problem then the soot issue will keep coming back.

 

So, you drove it for 5 weeks with no problems? Are you idling a lot? Was a regen done with laptop and the ash accumulator reset?
The DOC is the first device in the after-treatment system. It is a flow through filter that contains precious metals to start the oxidation of hydrocarbons, carbon monoxide and unburned fuel and oil. Both the DOC and the DPF are honeycomb ceramic filters.
Check and verify the simple inexpensive things first: air filter, check the intake and exhaust piping with either air or smoke. You need data from the system to see what the parameters are and if anything is off. There is a normal range for many parts of the aftertreatment system. Differential DPF pressure which is the difference between the inlet and outlet pressure of the DPF. Are the injectors running rich? NOx in and NOx out..... Maybe there is a problem with the 7th injector that is not setting a code. The engine may just be running rich and producing too many hydrocarbons.
The DOC and SCR (not that the SCR which controls NOx is your problem) are similar to a catalytic converter in a car. Eventually the precious metals wear off and don't react with the exhaust gasses to do their job and eventually need to be replaced. If all the data checks out then I would suspect the DOC.
Below is a good thread. DOC can/should be cleaned when the DPF is cleaned. With your 710k miles it's probably time for a one box.
How long is the Detroit One-Box supposed to last? | TruckersReport.com Trucking Forum | #1 CDL Truck Driver Message Board (thetruckersreport.com)