[plasticplant]

Finally got the diagnosis - DEF reductant tank reservoir heater needs to be replaced. I thought that might be it, but odd no CEL.

I know I'm way late to the party on this one, but I had that same repair. I didn't get the DEF light, but I certainly got the CEL. Strange thing is, I never got a reduced speed message. I drove with the bad tank heater for almost 2 months before it was repaired; and this was when I was putting 25k miles on the car a year.