My 2009 Prius sitting in a garage for over a year

What happens if you try to go out and start it right now?

 

you probably need a new 12 volt battery $2-400. and possibly a charge of the hybrid battery, maybe a few hundred.
change the oil and filter (under a hundred) and you're good to go.

follow the maintenance schedule that came with the car. how many miles on her?

 

Try it and see. Get a 12V jump if you need it. No sense spending money until you know what, if anything, is wrong

 

That 12v battery is very likely completely discharged, and has been for 8 months or more. I would be wary of performing a jumpstart with a completely discharged battery. Either get it charged and tested or just replace it. Then attempt to power up the car.

The first press of the power button will result in many warning lights staying on due to the previous loss of 12v power.
The second press of the power button should result in the car going to READY and those lights clearing.
Any that do not clear are likely legitimate.

The large hybrid battery is what turns the engine to make it start. Depending on the condition of the individual modules in the hybrid battery, some may have self discharged to the point of causing the hybrid battery to 'code out', but may still be strong enough to spin the engine for starting. If the engine starts, it should stay running and charge the battery until it's at least at the minimum 42% SOC condition. Also, you may be able to charge it further by "force charging" the battery. I typically do this by holding the car in place with the foot brake and pressing the accelerator as needed to keep the engine running (while watching the center screen (mfd) to ensure the arrows indicate the battery is being charged. It may charge like this while in PARK also, I just have a habit of doing it in READY.

If you're fortunate, the modules may have survived being idle for a year. If you're unfortunate, they may have discharged to the point where they're not even able to start the car engine.

 

The good news is many people think the 2004-2009 Prius is the best combination of size and reliability in a Prius. The 2010-15 models have many high dollar problems including engine failures. The 2016s up are reliable but are smaller. So getting yours running, even if it costs a few thousand, is worth it. Even if it is only for dramatically increased resale value.

Like the others, your 12v battery in the back is sure to be dead. Some might try to charge it but you might as well replace it. If it jump starts (be careful if you or a friend tries) then drive it to an auto supply or dealer for a prearranged battery installation. Otherwise get somebody to help remove the 12v battery and take it to the retailer as a core. With a new 12v battery, start it and drive it for a half hour or more before having the oil changed.

 

if you have triple a, they will give you a jump start so you don't have to have it towed, or you could buy a jump pack and learn how to connect it to the jump point under the hood.
towing a dead prius is difficult

 

Just to reiterate, if you can jump start it (be very careful to not put the jumpers on to wrong way around), you can drive it to have it serviced. No need to tow it.

 

Post 6 released late indicates she jumped it and it runs.

 

Exactly.

 

I would not suggest starting any NiMH based hybrid which has sat that long without first putting some charge back into the pack. It will have self discharged substantially, and might be far out of balance. Or it might be completely balanced - with all the cells very near zero volts. (It is a great way to balance a pack if you have a couple of years to kill. More often this comes up in packs like this one, which have been in cars sitting unused, or forgotten on a shelf in a warehouse.) Making the pack start the ICE motor in that state could reverse polarize some of the cells and damage them. Since most people will not be able to charge the pack, the safest thing to do is to have it towed to a dealer or some shop to have it charged. The 12V is probably shot, have them swap that at the same time. It will still start with old fluids, as long as nothing has leaked so much that too little fluid remains. Also, year old gas? Bad stuff. Best to have it siphoned out and put in some new gas, rather than pump the old stuff through the fuel system.

 

No need to siphon out fluids. Its not like it was flooded.

It is technically impossible to siphon out everything anyway. If you are concerned, have the oil changed again in 3,000 rather than 5,000 miles.

The engine lost some of its self tuning parameters with the loss of 12v which will retune shortly. Use brand name gas like Chevron, Exxon or Shell for the next handful of tanks which will reduce any valve deposits. Don't use any oil additives ever.

The tire sensors have batteries as well but they wear out after nine or ten years. Just replace the sensors when you can.

Finally, the smartest maintenance procedure for any car and especially a hybrid is to drive it every week. Regardless if you need it or not.

 

It had only 1 bar or less gasoline left, not siphoned out after multiple requests. I added 5 gal gas on top, as I had to drive more than 50 miles before e-check (after OBD by e-check people).

Anytime the 12v battery is disconnected, the fuel level will default to one blinking dot until it recalibrates itself. This can be 5 minutes or 5 hours or more.

A while back, every time I did an HV battery job, I would disconnect the 12v battery. I stopped doing that due to the confusion it would cause. After the battery work, customer and I would take car for a test drive with techstream connected to verify everything was good. I can't tell you how many times customer freaks out because fuel gauge showed 1 blinking dot and INSISTED on going to gas station because we were about to run out of fuel. Then they freak out because it would only take 3 gallons to fill up. Then during test drive, it goes to displaying full.

As for siphoning, modern gas is good for a few years. My father in law passed away several years ago. My wife inherited his truck. It sat at the house for about 3 years, never started or moved. When wife was ready, we put in a new battery and cranked it right up. Still couldn't move it because the brakes were rusted together, lol, but it fired right up. Another note about siphoning gas.....it's nearly impossible due to anti-siphoning construction in modern cars to keep fuel from being stolen.

 

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