[sapardo]

I have the exact same car which I got at about 42K miles. Same issue, I have taken it in about 4-5 times in the past two years for the PA158 error code. On the second visit they installed a new catalytic converter, but the DPF lights keeps on coming back on. It's frustrating because the car is in really good shape. Even though it's still under the extended emissions warranty I finally got the VCDS interface. So last time the light come on I just did a forced nox regen myself and after a 50 minute drive the light turned off. It seems like there are so many cars with that same issue, they should hand out a free diagnostic tools with them 😆. My thermostat seems to be ok, so hopefully I can get by with doing the forced regen once in a while.

 

[sapardo]

I did check the thermostat according to the TSB and it is fine. I did notice that the temp needle needs a while to get up there as well.
The dealer put on a new catalytic converter on my second visit. So yeah, I think that my light comes on due to driving habits. I mostly use the car for work, so if my jobs are out of town there's a lot of freeway driving. But living in the San Francisco Bay Area, we're back to more traffic jams and earlier rush hour traffic.
Since you've replaced your thermostat, have you been having no more NOX issues?
And thanks for all the info, it's been really helpful.