Capacitor issues, other than the MFD?

Discussion in 'Gen 2 Prius Technical Discussion' started by pasadena_commut, Mar 6, 2026 at 1:13 AM.

  1. pasadena_commut

    pasadena_commut Senior Member

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    It is common for the MFD to fail because an electrolytic capacitor used by Toyota wasn't quite the right capacity and over time it degrades to the point where it cannot do its job. That was a design failure, even though it took a few years to show up, it wasn't really the typical sort of capacitor age failure.

    These cars are getting up there in age, mine will be 20 next year, and at that age it is fairly common for this type of capacitor to fail. They swell, leak, or just get so far out of spec that they cannot do their job anymore. This can cause big problems in a car if it happens in the ECM. However, it seems not to be common in the 2nd Gen Prius, at least yet, as I have no recollection of any posts here describing an ECM failure from capacitors aging out. I have never opened a Prius ECM. Did Toyota just use really high quality electrolytic capacitors (in which case they will fail eventually, it will just take longer) or did they employ solid state capacitors, which last much much longer than the electrolytic ones?