I just had a hybrid battery replaced a week ago and I have lost 10mpg since. They are telling me the cause is possibly a dirty throttle body. I'm just wondering if anybody has had similar situation or any other advice.
With what? OEM new or a "rebuilt" of second-hand old modules? So, they reckon the throttle body mysteriously gunked up at the exact same time they replace the HV battery? In any case, you will need to run three or four tanks of gas and then average the MPG over them to get a better idea of your current MPG. Ideally, you should have been recording your MPG per tank for some months before you had the battery swapped, otherwise, you don't really know what average MPG you were doing.
It's getting cold... MPG's for me are down as well & to be honest, that's the first thing I'd suspect as the culprit. So like dolj mentions up there average this out after a 5 or so fill-ups and see. Secondly, and you may laugh at this, but check your tire pressure. That's a big mpg reducer & the person who did the work on your vehicle may have adjusted the pressure. Also just curious. Is this a "rebuilt" battery or new from a Toyota dealer? There are literally hundreds of threads here regarding those rebuilt batteries. Very, very few are complimentary.
