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Well, I just finished running my OBDII scanner and zero error codes current or pending, so fingers crossed this only crops up intermittently (the first and only previous one was just over 1 year ago with this event being second wrench for the same issue). For what it's worth, I ran through the "reset"/erase error codes. Still don't see how a yellow wrench icon does not generate any error/fault code... Greg

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.

The HVB is what runs the two electric motors that conspire to start the ICE and to get ICE torque to the wheels, remember? The 12v battery is just for the accessories and the power relay that lets juice out of the HVB. If the HVB is totally dead, your car is bricked. But there's a long way to go from "can't run on battery for long" and "not enough battery to start the ICE".

I stopped trusting the dealer, sometimes you get better service from a small independent repair shop. My dealer seems to have too many cars to work on and they are on a tight schedule, so it seems they work more like on one of these quick lube places. Just trying to get the car out as quick as possible. Since I've started doing my own service, I've noticed a lot of sloppy work was done from them. Like some screws are missing from the under engine cover and my lug nuts are swollen from overtightening with the impact gun.