Prius Battery

I own a 2002 Toyota Prius. I got the prius battery replaced in April 2013 however, I’ve recently experienced two breakdowns in the middle of the road. I think the car shut off because the battery overheated…the warning light came on and then the car just shut down. I waited about 10 minutes each time before turning the car back on and it successfully turned on. Ran a diagnostic when I got home and it read the same codes (Cylinder Misfire and Fuel Air Metering Auxillary Emission Controls). Could there be a faulty cell in the new battery? All the codes cleared and it ran like normal. The engine sounds fine.- See more at:

I’m pretty sure if the battery was the cause, you would get appropriate trouble codes. I recommend you post the alphanumeric codes (not the interpretation of them), so someone wiser than I can help you with this issue.

Did you replace the starter battery? OR the hybrid battery? Which do you think overheated? If the starter battery overheated, not much would happen (it is a dumb lead-acid type) and it is unlikely that Toyota put a sensor on it. If you are concerned about a bad cell, put a voltmeter on it, it should read 12.7 volts or so with the engine off and 14.5 or so running.

The hybrid battery is a completely different matter, it is a nickel-metal hydride type. If that overheats, really, really bad things can happen but is is not affected by the starter battery. AND Toyota has protections built-in to prevent those really bad things from happening with the requisite OBD-II codes to tell you so.

@Mustangman - the 12V battery is for the accessories, the ‘starter’ is one of the two big electric motors and it runs off the main battery.

My bad @texases, Replace “Starter Battery” with “Accessory Battery”

I don’t think the battery is the cause of the diagnostic code. You may have two different problems.

OP, the cylinder misfire/fuel-air metering, if that repeats, is something that needs to be resolved with prudent speed. Otherwise you may end up damaging your car’s very expensive cat converter. I expect you have some problem with an emissions device like the EGR sticking or an evap problem or a vacuum leak which is the root cause of this problem. If you can post the exact codes your are getting, someone here might have some experience and can offer some guidance on likely causes at least.