Regen interapting because high temperature

I had a similar problem, if I recall it was the pre dpf "million dollar flex pipe" that breaks down internally and plugs up the inlet of the dpf. A decent shop can stick a little camera in there to confirm instead of pulling it all apart on a hunch. Just food for thought -I could be wrong. There have been a bunch of common issues with mine and they all just blend together...junk junk junk.

By the time the dust settles - new flex pipe, dpf bake, new clamps and gaskets ugh. And of course flex pipes are not covered under warranty.....
I deal with a killer shop though, who squeezed Volvo to eat the cost of the flex pipe ($800ish)

......time to delete!

 

So i've had this problem a few times, does it put out any kind of fault codes besides spn 5246 when this happens or regen is going thru like a 5394 fmi 1 i believe it is, if you have vcads try to remove the fuel line going to diesel doser and see if there is a constant leak coming from there most of the time it will leak air, this was the case in one truck the doser block was actually overfueling all the time but you have to go thru diagnostics to activate it and see without engine doing regen, i've had the flex issue as well that @sirjeff is talking about and the last time this was happening the injectors were causing to much compression in the fuel giving the diesel doeser a really messed up reading causing it to do exactly the same thing you are describing, would not suggest to take it to volvo the first thing they will tell you is that the catalyst is cracked, but that being said its not an easy issue to figure out on your own, i need a little more info as far as if there is any fault codes that come from the engine after the regen fails,

 

From looking at the code, I would drain the DEF tank and check the lines for blockages, then put new fluid in. You might be able to find a video on cleaning the DEF doser if it looks blocked up. Maybe try running it through another regen to see if it clears the code. At that point, you're looking at replacing the DEF doser or aftertreament control module.

I've never personally done any of these tasks, and I'm not a certified mechanic, just going by the list of possible causes for that code. When our ACM was replaced by a non Volvo dealer, they ended up charging $1200 more than the estimate because they had to have it programmed by Volvo. They also replaced the doser, but they ate the cost on that part because they felt bad just throwing parts at it and spending like 7 weeks unable to diagnose/repair it. It was a different code than what you're having.

I hope that helps.