What are the symptoms of a failed hybrid battery?
The most common visual indication that your hybrid battery has failed is the notorious red triangle on your cars dash. It’s the same one that comes on if you open your door with the car in drive.
Other indications include the hybrid system trouble warning (top left on multi-function display, red box w/ a car w/ an exclamation point through it), several yellow lights including check engine lights, VSC, ABS, ect.
You may hear your gas engine (ICE) revving higher than normal. This is because your cars computer senses something wrong with the hybrid electric system so it is transferring all of the load the gas engine. This also results in low power, poor acceleration, and bad gas mileage.
You may hear the battery cooling fan running on high (back seat on the passenger side is the intake for the fan). Your car’s computer is trying to protect the battery from overheating and causing further damage.
If you take your car to a local auto parts store (like AutoZone or O’Reilly Auto Parts) they can read the trouble code or codes that are causing the check engine light to come on. The most common code to get when your battery fails is P0A80 (Replace Hybrid Battery Pack), it’s not uncommon to get a weak battery block code which are P3011 thru P3024 depending on which part of the battery failed. Any other code that starts with P0A is most likely pointing to a problem with the hybrid battery.
Signs that your battery may be getting ready to fail
If your battery had a good charge when you turned it off and after sitting over night it shows empty. This failure to hold a charge is normally followed by rapid charging and discharging on the energy monitor while driving. (the reason for this behavior is discussed later, see Why did my battery fail?)
Any poor power or mpg performance with greater than 150,000 miles on your car should be considered a warning that your battery is not performing properly.