101k now / Never done any maintenence, now i'm getting poor mpg. What do I do?

I'd worry the dealership would be clueless and the only thing you'll notice is that your wallet is lighter

 

If you haven't had your wheel alignment checked yet, you might consider having that done next.

Have you taken a road trip of 100 miles or more, recently? I'm wondering what mpg you can obtain under conditions where you are driving at relatively constant freeway speeds.

 

Did you clean or install a new Mass Flow Air Sensor? I heard that could be one cause of bad mpg's if it gets dirty?

 

You are running out of easy things to fix, and the lack of DTCs is curious. Increased PSD friction maybe ? I would not delay in changing that fluid.

 

PSD - Power Split Device, the "planetary gear set" that is the core of our Prius transmission.
HSD - Hybrid Synergy Drive, The overall system which includes the two Motor-Generators (MGs, which are packaged together with the PSD) and the firmware in the various programmable controllers.

Basically all of these terms are used interchangeably in these discussion groups.

JeffD

 

Yep, the trans fluid. Good Luck!

 

the spark plugs, transaxle fluid, and cleaning MAF, throttle and PVC + new engine air filter = i got my 45-50 back. But same rules apply as when I drove the car new and got 45-50mpg normally, in order to get that 50mpg I can't do my normal 85mph. A trade off I'm okay with that. with tire rotation, alignment, and 50psi in tires I'm back to normal mpg. money i saved from going to dealership in O.C. I drove to SF for the weekend, was nice. car performing as usual, fantastic even at high rates of speed. You had to order the trans fluid, was your local dealership was out of ATS WS?

other then that try seafoaming it? lol!

 

I assume you've checked the tire pressure? (optimum for best pg is 40-42psi) When did you last check/replace the engine air filter? Dirty/clogged air filter can reduce mpg significantly.

Whoops! I see you've done that already.

 

By any chance, did you install roof rack or change new wheels / tires?

 

OP, I think you are right in considering the traction battery if a transaxle change does not improve the mpg. Try PM'g Pat Wong or Bob Wilson for advice how to test.

The CA warranty on the battery is 150k miles.

 

Warranty, covers failure of one or more cells, which could equivacate to LOW mpg (lower than your normal) So.............does one go to the dealer complaining of low mpg OR a bad HV battery. I'm presuming a charge for the HV check.:cheer2:
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Here is an article how one garage tests the HV Battery

Predictive battery failure analysis for the Prius Hybrid