Looking for some advice on a problem child. I've got a 2019 Volvo VNL (N214077) with a D13TC and the "one box" setup in the shop with a P0420 fault. This is the second time in the shop with the same code. First time, I verified ECM & ACM software levels, verified hc doser lines and flow test, ran AHD module self test, tested t1 sensor, removed DPF to find an excessive accumulation of pink ash on the face. Found EGR cooler to be leaking. Replaced DPF and EGR cooler, ran regen and verified temps. Now the unit is back, I've still got combustion gases in the coolant (my fault for not checking the cups the first time) and the P0420 code. The DPF looks great, but I'm curious if the DOC is sensitive to coolant poisoning and needs to be replaced, or if I fix the source of the leak, will the DOC return to normal efficiency. Any help is appreciated!