Hi all Posted this in the Gen Tech section possibly wrong place so, again- We have three GenII Pri's in the family. The three located in Arizona have had Inverter pump failures each during a peak heat month. All have been replaced on warranty, mileage from 35k to 85k with assurance that no long term damage has occurred. My '04 has 85k and it's failure occurred a few months ago. A few weeks ago noticed that one tank average had dropped from 50 +/- 1 to 43 +/- 1 MPG. Checked tire pressure, oil level, brake drag, DTC's etc and all good. Could the inverter semi-conductors be going bad with no DTC's? What else could it be??
Usually a semiconductor acts in a binary function: it either works or it doesn't. So if your car becomes READY and there are no warning lights, I would look elsewhere for the reason for an mpg decline. Also, having mpg low with one tank is not enough to be worried. Who knows, you might have been shortchanged at the pump, the energy content of the fuel might be below normal, etc.
What was that news I recently heard? Something about the gas expanding in underground tanks when temps outside become high, thereby making pumps indicate more fuel was pumped than what actually flowed into tank.
Even if the little processors on the inverter electronics module are flash-based, I seriously doubt a dealer has any way to reload them. Main ECUs, yes, something as embedded as that, no. I spotted nothing that looks like a programming interface on the control board. . _H*
Not to support anecdotal theories, but I kinda noticed the same thing after mine went at 101k miles. MPG was never quite the same after. I kinda thought it was the overpriced injector cleaner they put through as well.
I think it is possible for transistors to degrade after operating at too high temperatures. The dopants could diffuse away from where they are supposed to be.
The '04 has now had at least 4 tanks of fuel and still 45 or so average on MFD and by tank calculation. Slightly better due to the cooler weather. 10 % MPG reduction is not worth a huge effort but it's got to be related to the pump change. Now it's comparable to my wife's '06 fuel efficiency.