Red triangle + check engine after boosting battery

Was the car running normal and no lights on when it sat 2 months ago? When that red triangle comes out, it's suppose to warn you of a danger in driving your car. You should not have driven it 20 minutes and hoped it would turn off.

You need to get the DTC codes on the car, it will tell you why the lights are on. But without that, guessing is the only approach, and guesses can be wrong and can damage your car further.

 

I'm not entirely sure what you mean by "wont go into electric mode". The Prius can't be driven at all if there truly is no electric mode. The electric motors/generators are absolutely crucial to the operation of the transmission, whether or not the engine is running.

Anyway, if the car is actually driveable then I'd just drive it for a while to charge the 12V battery and then try disconnecting it (the 12V battery) for a while and reconnecting it to see if it clears the errors. You probably should also try a battery charger on it if you've got one.

 

If everything was running normally when you let it sit, chances are the battery just went dead. Disconnect the battery, charge it up and see if it'll hold a charge. If not, then replace the battery. By disconnecting the battery, everything should be reset when you connect the battery back. Hopefully everything will be back to normal after you charge/replace the battery.

 

Yes the 12v battery. The batteries from the dealership are not deep cycle batteries. Others here have been able to recover/recharge them without a problem if they fully charge them completely again (within a short time of the discharge).

Worse case scenario, you just return the battery for another one under warranty. You should have a 24 month full exchange warranty on that battery.

Next time you let your car sit for a prolong period of time, you should turn off the SKS function on the car. There is a button under the steering wheel of the car to enable and disable that feature. That is most likely how your battery drained.

 

It's not really good for them to go flat, but if it's fairly new it might still be ok. If you've got a charger then I'd disconnect the battery and do it that way. You want to disconnect the 12V battery for while to try and reset the codes anyway.

If you don't have a charger you could try just driving it around for a while, but remember that it charges pretty slowly in the car. It may takes many hours of driving to get anywhere near a decent charge level.

Ok, no problems. I guess that must be something to do with the error codes. At least it's reassuring to know that if it is driving at all then we know that the electric motors and inverter must still be working. So hopefully when you get the error codes reset everything will be back to normal.