Metal valve stem caps. Ugh...

Letting a dealer near the car to mess with non-OEM items did not help the situation either.

 

I did that once for the 5K tire rotation. Based on that experience I chose to do the 10K oil change myself.

 

We don't get those free initial services up here. Maybe lucky we don't.

I just went straight to DIY with this Prius, never regretted it. Last car was an 06 civic hybrid, with oil change spec of 3.2 liters. I gamely went with dealership service at first with that car, thinking warranty and all that. Gradually twigged that they were routinely dumping in 4.0 liters at every oil change, went back to DIY.

Our Toyota dealership is better in that regard, use bulk oil (the same Toyota oil that comes in the bottles, yes Ed, and whomever else wants to weigh in) and pre-measure for oil changes with big beaker/graduates, the precise amount spec'd. No "dumping in the rest of the bottle".

 

Isn't it illegal for them to not ask you first before repairing/charging (at least for the charging part, gratis repairs are fine)? Or are your state's consumer protection laws different?

Asking you first would at least give you the theoretical option of acquiring a more reasonably priced sensor elsewhere, and bring it back to them for installation.

 

Another option would have been to put your spare tire on, so that you could drive to a regular tire shop for a more reasonably priced repair. No tow required.

I'm sticking with the position that in my state, consumer protection laws concerning automobile repairs forbid them from forcing that overpriced TPMS sensor on you without advance permission from you.

 

They probably didn't know about dissimilar metal corrosion effects, it's not within their remit.

 

Won't that scratch the roof ?

 

When I took my Prius, it had the shorter regular caps that go on non-TMPS stems. Had to go get the longer caps that fit completely over the threads.

 

Perfectionist !

 

Never seize works to keep the metal caps from corroding, but sure is hard to get off hands after an air check so, I went back to the plastic caps.

 

Guess I'm the only one here that never had a problem with metal valve stem caps...cars, buggies, bikes, law equipment, aircraft...

 

I never had a problem back in the UK (North Devon, then Oxford), but then I moved to New England and was introduced to road-salt and all the other crud which gets on the roads, particularly in the winter!

 

No - make that 2 - I've not had a problem either. We don't have salt on roads.

 

Sorry but I can't say I have too much sympathy for letting that happen.
TPMS is not perfect and you should be checking your pressures manually at least twice a year, spring and fall; quarterly is better.
Had you been doing that, you should have caught the problem early.

In about 55 years of owning and driving all kinds of vehicles, most with metal caps, I have never seen them corrode like that.
Something unusual must be at work here.

The add-on TPMS system I put on my RV cautioned that valve stems come with 2 different kinds of metal threads and you must get TPMS transmitters made of the same kind of metal........or electrolysis would cause corrosion.
Maybe that is what caused your problem ??
(Edit) And after seeing that these were added by you, I think it is highly likely that the metals were incompatible, especially when you add a little road salt in the winter.

 

I had one of the TPMS valves (just the shank) corrode so that the threads wore down and were ineffective, but was able to fix it with a kit I found on amazon:

…which includes drilling out the stem and re-tapping the inner thread before fitting a new core. The TPMS stem is made of aluminium which explains why the corrosion occurs. Other stems I've used (both when I lived in the UK and when I came here (USA) in the early 1980s) were made of brass which doesn't corrode in the way aluminium does!

 

Aftermarket tpms are 20 ish dollars, any tire jobber can code them to your car, I agree, check your air monthly, you would have found the metal caps to be failing, the dealer is an independently owned for profit buisness, the techs are each different in their ability, your issue is with the dealer, not Toyota.
You should have a stem tool to check stem tightness of every tire, they like to be cleaned and oiled periodically, the tire sidewall pressure is half the bursting pressure.

 

Perhaps I'm just lucky because I have this "bad habit" of checking my pressures and fluids regularly. I hesitated to suggest schrader tools and lube with the Prius mindset.

 

Yeah, if you regularly check tire pressures you'll not have problems. Similarly with license plate bolts: I take the rear plate off pretty much every time I wash the the car, and occasionally put a drop of oil on the bolt threads. Someone here had the bolt corrode in place, the head snapped off when they tried to unscrew it.

Some of the plastic under-panels near the rear suspension are held on by by bolts into weld-nuts. Those are definitely worth visiting sooner than later, they can rust badly.

Also, whenever I'm going in for new tires, I take the valve caps off; that way I've always got some spares.

 

The underpanel bolts you referenced love anti-seize. I used high temp nickel.