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Take it to a battery place they will load test it for free.

No trouble, Ford dealer had best price. It was the last one they had in stock though with $18 core charge. Autozone and O'reilly both had them too as an equivalent but looked like the same battery with different stickers.

We changed 12V battery in my daughter's 2013 Hybrid this week. Replacement was $199 at Ford dealer. This was the cheapest price I found and cost less than non-ford solutions. Old battery lasted 7 years. Had a problem removing the plastic clamp on the bottom of the battery. The bolt got loose but failed to fully remove. Bolt was a little rusty and it was spinning the threaded nut under the plastic clamp. Was able to reach under the car and grab onto the bottom of the threaded nut with pliers to keep it from spinning for full removal. Previous battery was replaced in 2018 by ford dealer that offered a free install but unfortunately they over-tightened the nut on the Positive + clamp and that cracked the clamp body and it came apart when I removed it. Ford doesn't sell just the broken clamp part, they sell an assembly of the parts connected to it for $320. However I was able to get a universal clamp at autozone for $10 that worked just fine. After install charged the new battery fully and then ran the manual procedure to reset the battery age to 0. That process worked and was able to the run the radio 10 min after turning the car off.

Guess I would try disconnecting 12V battery for a minute. Master Reset!

Try 10mm , this is what my other Ford uses the battery bolts.

Early model SE's had problem with water intrusion in the wiring in the front of the car. I think there was TSB about it. May not be related to your problem but sounds similar.

What year is your car and do you know what version of sync you are running? If you are running 3.8 or earlier I can send you 3.10 version to try but if you have a hardware problem it may crash and burn when installing.

Glad you found a great place to get your car repaired. I hate the mentality of just changing stuff until fixing the problem at your expense. Doesn't anyone troubleshoot anymore?

If there is a light sensor to adjust the screen brightness depending on the ambient light perhaps that is the culprit.

My 2013 SEL Hybrid with about 70k after 10 years averaged about 40mpg in the winter and about 50mpg in the summer. That is using the seat heaters and heater after the engine warms up. Lifetime was 45mpg. Using the ICE going up hills and electric on flat lands and down hill when possible. But it doesn't get super cold here normally in PNW. Didn't notice any drop off in mpgs.

Are you sure it is not just the colder weather and running the heater more killing your mpgs? Also driving higher freeway speeds will do it too.

I was thinking fuel injector , but what do I know so I asked chatgpt AI. Here is what I got back... It sounds like you're experiencing an intermittent issue with your 2017 Ford C-Max Energi, and the fact that the yellow wrench light appears along with engine clacking and power loss points to a possible issue with the engine or transmission. The fact that turning the car off and on temporarily resolves it suggests an electrical or sensor issue, though it's tricky without any specific error codes. Here are some potential causes and things to check: Battery and Electrical System: Since the battery was replaced recently, it's worth considering that the charging system (alternator, wiring, etc.) might be causing the issue, especially if the car's electrical system isn't functioning properly. Even though the dealer replaced the battery, other electrical faults (e.g., a failing alternator) could cause power loss. Throttle Body or Throttle Position Sensor: The clacking and power loss could be related to a malfunction in the throttle body or throttle position sensor. This could cause erratic engine behavior, and the system might be resetting when you turn off the car. A diagnostic scan might help here, even if no error codes are currently visible. Hybrid Powertrain System: Since the C-Max Energi is a hybrid, issues with the hybrid system (like the electric motor or hybrid battery) could cause engine performance issues. A hybrid-specific diagnostic tool would be needed to check this. Transmission Issues: The “clacking” noise could also be coming from the transmission, which might have an intermittent fault, especially if it’s related to the power transition between the gas engine and the electric motor. Sensor or Module Failure: There might be an issue with one of the many sensors (e.g., crankshaft position sensor, camshaft position sensor, or fuel system sensor) or a module that's not throwing an error code but causing intermittent failure. A more thorough diagnostic might reveal this. Since the issue is intermittent and there are no error codes, I'd suggest having a Ford technician perform a deeper diagnostic scan, including hybrid system checks and possibly checking any updates for the car’s powertrain control module. It could also be worth checking the service history for any outstanding recalls or service bulletins that might relate to these symptoms.

My son upgraded his 2016 c-max energi to the latest sync version a couple years ago but I don't think he had to upgrade the usb hubs. If you are going from sync 2 to sync 3 I think the usb ports are upgraded on some models. He got the sync updates from a non-ford site.

Must be an energi message, never saw that one on my hybrid. I bought our car in april of 2013 and it got great mileage all summer then when winter hit I noticed it would run forever before it would go into electric mode. Then I discovered turning the heater off or turn it down and use the seat heaters when the car was cold. After a couple of miles the car would be warmed up and could get some heat out with the ice running continuously. Even doing that I still took a hit on mpg's in the winter.

For starters, I would measure the 12v battery without the charger and see what it reads. Can you put the car in a garage and warm it up to see if the problem is temperature related? I've seen the hybrid battery that low a couple times but it didn't affect the operation.