BL1999

So I took the liberty of buying a scanner and it came up with two codes, U0253 and P0420. I assume the former is just a false flag and it's nothing to worry about but the latter may be the culprit of my issue at it notes poor fuel economy and a bad smell which somewhat occurs if I leave the AC running without any cooling. Of course I could be mistaken but it's a possible lead.

This happens during the driving cycle a multitude of times before hybrid mode starts to act properly. If I have to make a quick stop then I activate my car again, the same result will happen no matter how long I've been driving for throughout the day. I believe the propulsion stage of the car startup may have problems detecting the hybrid power reserve on the HV battery as it tends to start completely empty if I don't charge my car overnight. Before the incident, there was always a small amount left on the reserve and it would give me power upon braking at any point of time but now it acts like it has to force the charge itself when I'm driving before it starts to function normally.

I only had to replace the 12v battery which as previously mentioned made the vehicle perform normally aside from my car struggling to smoothly transition into hybrid mode. From what I could tell, the HV battery didn't appear to be affected by the event. I did drive the vehicle around with the old battery as I tested it with jumpstarting but it would die upon turning off the car and that's when I first noticed the particular issue with hybrid mode. To add clarity, this would happen no matter how much excess power from hybrid mode is there, as if the car cannot detect the power properly until I drive about half a mile where it functions normally. So if I run out of HV battery and it comes to hybrid mode, it would normally be topped off in power but accelerating beyond a certain speed threshhold will make the car forced to run on gas even if I decelerate for some time. Some of the energy will still be allocated when I do approach higher speeds (around 40 mpg) but only if I go down say the Interstate road to reach those kinds of speeds, otherwise the engine ignores hybrid mode entirely.

I am having an ongoing issue with my Fusion Energi SE 2018 forcing to charge with regen. Back in May of this year, I left my car charging for the entire day to find it completely dead upon trying to start it up. The only conclusion I could come up with is that a bad volt from the weather shocked the car and fried some components and the main battery. I ended up having to replace the battery since it looked like it went bad in that very instance which fixed the functionality of my car for the most part. However, a symptom came up where the engine will not immediately go through regen and go off the gas which in most cases kill my MPG. I have to drive about half a mile before regen starts kicking in. If I leave my car without a battery charge throughout the day, it shows that the battery reserve is depleted entirely and it has to boot up the engine to compensate. I approached a dealer to see their impression and they offered $150 to inspect the car over a period of time with the notion that the battery warranty will come in effect since my car is under 100k miles but I am skeptical of their policies and want to ask here before I decide to do it. I just want to know what part could've been damaged and if it can be covered with the warranty.