ZARTT

Does a 4Runner 3VZ-E engine computer lose it's software if left off the battery for a long time?
Does it have to be reflashed???

Thanks
Art.

DJ99

No. It's in there for good.

RMA

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abecedarian

Nope. The ECU won't forget how to work.
However, it does have some capability to remember some things like fine tuning the fuel mixture, trouble codes, etc. which are forgotten if the power is removed from the ECU, but will be re-learned over a few trips.