06 prius mpg gone way down

An 06', thinking the traction battery is due, if you spend the 2500$ you get five years of almost a brand new Prius, depending on tires brakes and struts, go to a Toyota dealer and get an estimate, possibly two estimates, at the moment the ice (internal combustion engine) is doing the work, I'm assuming, and the traction battery is along for the ride.
If you save a 1000$ dolla s on a rebuilt traction battery, well I'd advise buying a new one, but it's your money.

 

First you should be checking your mileage with the "manual" method and not trusting the onboard display.

If you are already doing that.........sometimes a sudden drop in mileage is an early sign of the HV hybrid battery failing.

10-11 years old with 200K miles is a good run for the HV battery.

 

Are you in habit of reseting the average MPG on the consumption screen every time you fill the tank?

If not, the average MPG will have been averaged over several 100,000 miles which means as your HV battery was (possibly) declining you will not have noticed it.

When the 12 V battery was replaced the average consumption will have been reset back to zero, and so now represents a more true value of your average consumption. It may well improve a bit, if this is below your normal average, but the apparent drastic drop will be because the average consumption meter was reset back to zero.

The lack of power symptom (and the low MPG) does indicate a HV battery on the way out, expect to see some error lights appearing soon.

 

If I remember right, a 2006 Prius has a gas bladder not a actual tank?
So, I'm just wondering how you are calculating your gas mileage.

I'm thinking a "new" gas bladder might of changed everything. Might not be holding as much fuel as before.

It certainly could be a sign of a failing HV battery but I'd want to evaluate MPG manually. Curious if your new gas bladder might be holding a lot less fuel.

 

It has a bladder inside the tank.

And no, it shouldn't change the dynamics much, especially the onboard average/instantaneous MPG on the MFD.

The bladder may cause tank to tank variances, but averaged over multiple tanks it should even out.

 

With what? New from Toyota or rebuilt (aftermarket company)?

 

What I'm wondering is if the OP has monitored how much gas his new bladder is holding.
Being entirely new, it may not be holding as much as his old one, which (if not paying attention to how much fuel you are actually putting in) could explain the sudden MPG loss.

Bladder "inside" the tank...is gas bladder.
2010 Gen 3 Toyota changed to a more conventional gas tank.

 

MPG = Miles Per Gallon = Miles Driven / Gallons used (refilled) = Actual Fuel Economy

MPT = Miles Per Tank = Miles driven form "F" to "E".

The "new" tank has a new fuel level sensor, from what I can tell; but have never seen any documentation on, the display acts like it uses tank LEVEL to guestimate fuel economy, instead of calculated fuel use (injector total "on_time" times "flow_rate") over miles driven.

Miles Per Tank is in no way equivalent to Miles Per Gallon for calculation of fuel economy.

 

Ok, one of your spark plugs must be fouled, have the obd2 port read, a plug missing will show up, if not, another traction battery....

 

But the most accurate way to really gauge your fuel usage is to reset your trip computer on fill up...have a full tank, drive until you fill up, note exactly how much fuel you have added and divide by number of miles driven. Then repeat....
That's far more accurate in my experience than any MPG that nearly any vehicles MPG software or feedback has ever given me, including the Prius.

So I disagree...how many miles you are going between fill ups, as long as you know exactly how much fuel you are adding at every fill up and exactly how far you've gone ( Miles Per Tank ) is a GREAT way to calculate for fuel economy.

I'm not saying I am right. It could be as complicated/simple as The OP does have a hybrid battery about to fail.
The only reason I'm promoting manual calculation of MPG and noting how much fuel per fill up, is the OP say's this MPG drop happened right after having a fuel pump failure and replacing the fuel pump and the "entire tank". Which makes me look in that direction.

It can't really hurt. Worst case scenario? The OP get's a real good idea what his MPG actually is, and his Hybrid Battery STILL throws a code and he still is faced with the same challenge.

 

No. You have absolutely no WAY to run a vehicle to the same fuel level each time and the inaccuracies of the level gauge leave much to be desired. The only way this works and it can, is if you run to empty, as in no fuel left. Then tank after tank, you can gauge any change in efficiency; presuming of course that you were no on an incline when you ran out.

It does not matter one iota, if you add 3 gallons or 300 at a fill (Prius or Big Rig), the math is still Miles Driven divided by fuel used.

 

I don't disagree with that. In fact that's what I've been saying all along.

" But the most accurate way to really gauge your fuel usage is to reset your trip computer on fill up...have a full tank, drive until you fill up, note exactly how much fuel you have added and divide by number of miles driven. Then repeat...."

 

...and repeat, repeat, repeat. Then average it over the course of multiple tanks.

You are correct in post #9. The new bladder may be holding a different volume than the old one. Even the same bladder holds a different volume every time you fill the car up. Averaging over multiple tanks is still the only way to even approach an accurate reading.

 

My 2006 Prius only has 67,000 miles on it. Is it the miles or the 12 years?

Are ALL Priuses needing a new $3,000 change?? I am pretty upset as I live in an area with zero public transportation (Georgia) and being a widow on social security I am very worried.

 

Yes, it's time not miles. All batteries fail eventually. My 06 only has 54,000 miles and needed the original battery replaced last year. I got a new Toyota pack here in Texas for $2500 installed. There are several choices for replacement from used (refurbished) to new with prices ranging from $500-4,000. Start your research now and you'll be better prepared for the eventual failure that is coming.

 

Took my 2006 Prius into Rick Hendrik Toyota in Atlanta with 31 mpg. I told the service guy David that I might need a new hybrid battery? He said “There are a LOT of things that can cause dropped MPG..let’s check them all.”

Previous maintenance a week before in Douglasville gave me all green boxes for tire tread, camber, axle, etc. “No worries.”

In Atlanta, two tires are nearly bald, and a chunk was taken out of inside side wall. (After driving 60-70 miles) 4 new tires. New alignment.
MPG now back to 47.

Glad I have an honest service guy...I HATE driving into Atlanta but I have to. Atlanta is the only major city in the USA with THREE Interstates running through it. I-20, I-75, I-85. Traffic REALLY sucks.

 

Anyway--hybrid battery pack was A-OK.