Aftertreatment issue

Hi, we have a 2012 freightliner Coronado with a DD15. This truck has been a pain since we bought it. The current issue is in the aftertreatment. It’s equipped with a one box. When the truck comes in at the end of the day we generally have to regenerate it with a laptop. Nothing unusual for this truck, but lately when it runs a parked regen, it melts the air line and heated def line at the metering block. It’s happened 4 times in the last 2 months, we’ve moved lines around, put heat wrap on everything, nothing is helping. This last time it melted, it took out the def line, air line, wiring harness on top of the one box, and all the sensors in the metering block, if it was plastic, it was dripping on the ground. So we’re replacing all the melted parts, and we took out the dpf filters to clean them, this was also done a year ago. I did notice the DOC had a good amount of soot built up on the face which we blew out. So anyone have any ideas on why it’s getting so hot all the sudden? Was the DOC plugged? Is the 7th injector dumping too much fuel? The codes were getting are for poor DEF quality but it’s not our DEF, and low DEF pressure. But that shouldn’t affect temp. I don’t believe

 

Well I just cleaned then whole one box system less than a year ago, but we took the one box apart and recleaned the dpf filters, there was pretty much nothing in them, the was a lot of soot on the face of the doc though so we blew that out really good, and I did notice the truck was surging during a regen which is generally a sign of a plugged doc or bad throttle valve, but it only surges during regen so I’m assuming it’s not the throttle valve. I never checked the differential pressure though. And we can’t get new filters. Freightliner only offers a whole one box or nothing.

 

Ok thanks for the input. We will try that