When this recall was first announced, there were some early discussions in this forum indicating that it caused a reduction in MPG, was not really necessary, and other negative comments. Now that some time has gone by, I'm wondering what the current thinking is on whether or not this software update is worth it?
good question. no one has come back to report long term mpg ramifications, and those that thought they lost some mpg's had no real way to measure it. i have held off simply because i don't accellerate hard or speed, which seems to be what causes the problem.
I didn't notice any difference after that latest update. After getting the previous inverter-related update, the one for protecting the inverter during hard acceleration, I noticed a slight increase in propensity to go into electric-only propulsion, that's all. With that earlier update there was a lot of negative outcomes, primarily mpg drop IIRC. There was/is suspicion it was due to incomplete/confusing/contradictory instruction to the service departments: it was prone to being misinterpreted, resulting in a messed-up update.
On the same NHTSA page where that recall announcement PDF came from, you can also find the PDFs of the Defect Information Report and of the TSB that contains the instructions the dealer will follow when doing the recall. https://static.nhtsa.gov/odi/rcl/2020/RMISC-20V369-2762.pdf https://static.nhtsa.gov/odi/rcl/2020/RCRIT-20V369-0509.pdf The defect report is interesting reading, and will tell you more than any number of us spitballing about what we think seems to cause the problem. A lot of the negative comments, as bisco mentioned, were people reporting MPG loss after not much time since the update and without much resembling even an 'informal' analysis of variance shoring that up, or people reporting 'obvious' reductions in acceleration, based on their butt dynos. It often sounded like they were reporting things they'd been predisposed to finding, starting from grossly simplified understandings of how the system even works, followed by assumptions about the 'obvious only way' the updated software could be changing that. I think I'd want to see more than that before assuming I know more than what the engineers learned about the problem. I had the updates done myself, because (a) I dislike surprises, in cars anyway, so I like the sound of reducing my likelihood of walking from the side of a road when I meant to be driving somewhere, and (b) I think I would even more dislike a conversation with somebody else's insurance company or personal-injury attorney where I'm explaining why I was driving a car with a known recall I had chosen not to get.
The people who reported lower mpgs after the flash update are the ones who has kept on going logs of mpg per tank prior to the updates and compared before and after numbers. The ones who reported no affects are the ones who doesn’t/didn’t keep track of their mpgs prior to the update. They have no base line measurement so I better the former.
Same, the highest rpm my commute is 2,500. Carfax keeps sending me emails saying I have a recall that’s overdue. I always mark it completed and the monthly email preveals. And carfax says my last oil change was 120,000 miles ago, that another monthly I can’t stop either.
Is that a fact, or something you assume when a person posts that they have no statistically-significant change to report? It takes a good record of data to analyze whether any apparent change was statistically significant, and that's whether your result ends up being that it was or that it wasn't. But when it wasn't, often people will just say so and move on. The null hypothesis—no significant effect—is the one you need to show the work to reject if you think you have found an effect. It's the easiest thing in the world to think you have seen an effect when comparing years of baseline data to a month of new data since something you just changed. Next to arguments over 12 volt batteries, it's probably one of the top PriusChat pastimes.
According to tstream as of 2021 when I bought the thing completely updated it says my Prius has all the latest updates to the ECUs and I have all those updates in the big file on the CF-13 computer that came from the dealer so I guess I have it unless it's newer than that?
The TSB (second link given in #4) has the updated calibration ID numbers in it. You can compare what Techstream is showing you to those to be sure you're up to date.
