I recently purchased a brand new 2020 bolt and a similar issue happened to me. I was driving to work last week when the service car symbol appeared. I pulled over and got on star to pull the code - P16EA. The car went into reduced propulsion power mode after I continued driving to work. I was really bummed out because the car is only a couple of weeks old with ~2000 miles and already throwing a code. I took my bolt into the dealership and after 1 week of ‘diagnosis’ they told me they were instructed by Chevrolet to reset the code and that I could pick up my car - they said that if the issue comes up again, the HPCM would have to be replaced. I got to the dealership, turned on the car, and the service car symbol appeared immediately....Hi all, just throwing this out there to share my recent scare with the dreaded "Propulsion power is reduced" message on 2017 Bolt. 28000 FLAWLESS miles, then one hot summer day (parked in garage, plugged into L2), I hit the remote start to pre-cool. 5mins later, turn ON to drive away and get the message (and service car symbol). Like I said, it had been PERFECT until then, so I was pretty startled. As I drove through my neighborhood it didn't seem weak, so I thought "maybe it was just a little hot from sitting in the garage, it'll probably go away once it cools off a little". But no, eventually I realized that power really was very much reduced and it wasn't really safe to drive. Parked it, then later that night (cooler temps), powered on and drove around just like normal - but the service car light still illuminated.
I used my OBD code reader and got a few codes, but little/no info anywhere. A few sounded like scary dead battery or main fuse problems. Anyway, the dealer took it in, "reprogrammed" something, and gave it back. It's been totally fine ever since (weeks of driving, all conditions and charge levels). I'll copy the service verbiage below, hopefully this helps someone in the future:
"Corrected by drive motor power inverter module reprogramming with SPS. Found DTC S P0AC4, P0AEE, P0BD2, P0BDC. Inspected and reprogrammed HPCM per TSB 18-NA-064 to correct. SPS code 17YN24133339."
Also wondering if anyone here can get their hands on that TSB, curious what it says...
All this to say, I’m really frustrated and I suspect some greater issue to be causing all of this. Maybe a faulty battery? I will be sure to update you with the outcome of my broken bolt.. I’m wishing I dished out the extra money for a model 3 at this point.