"Michael Pardee" ...
> "Tomes" ...
>> "David T. Johnson"...
>>>I have a 2006 Toyota Prius with about 50K miles. The check engine light
>>>came on a few days ago after the fuel filler cap was left dangling for
>>>two days after a fillup. The DTC code from the OBD2 scanner was P0440
>>>for "Gross Evaporative Emissions leak." I put the gas cap back on and
>>>waited for the check engine light to go out by itself. It never did. The
>>>prius (unlike some vehicles) does NOT reset that DTC code (and probably
>>>others) even when the source of the fault is no longer present. I
>>>manually erased the DTC code after two weeks which turned the check
>>>engine light off. It did not come on again. It seems to take a day of
>>>operation with the fuel filler cap off before the DTC code is set and the
>>>check engine light comes on but...once it does come on your only option
>>>is to take the car to the dealer or get yourself an OBD2 code reader to
>>>reset it. If the dealer says you need expensive fuel system component
>>>repairs, get a second opinion as there may be absolutely nothing wrong.
>>>
>> There are a few other things that one can do to reset codes without
>> having a scanner. One is to go to a place like AutoZone who will read
>> the codes for you [ostensibly in the hopes that you will buy the part to
>> fix it] and then let you push the button to clear the codes.
>>
>> Another is to pull the fuse that resets the computer. A third is to
>> disconnect the battery for about a half hour [same as pulling the fuse as
>> far as the computer is concerned]. The second and third ways I have not
>> tried in a Prius, but they have worked in my Sienna. I would have to go
>> look up what fuse it is [something like the EMT fuse or something (???)],
>> but that is not happening right now.
>>
>> Hope this helps,
>> Tomes
>>
> Worth noting: most ECUs are learning devices. Killing the power to them,
> by pulling a fuse or disconnecting the battery, requires it to relearn
> everything it knew. That is not always a bad thing, though.
> Mike
Yep, when I used to do this on the Sienna [before I got my scanner] I never
noticed anything different when I drove it. I am thinking that the defaults
are pretty good.
Tomes
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>> "David T. Johnson"...
>>>I have a 2006 Toyota Prius with about 50K miles. The check engine light
>>>came on a few days ago after the fuel filler cap was left dangling for
>>>two days after a fillup. The DTC code from the OBD2 scanner was P0440
>>>for "Gross Evaporative Emissions leak." I put the gas cap back on and
>>>waited for the check engine light to go out by itself. It never did. The
>>>prius (unlike some vehicles) does NOT reset that DTC code (and probably
>>>others) even when the source of the fault is no longer present. I
>>>manually erased the DTC code after two weeks which turned the check
>>>engine light off. It did not come on again. It seems to take a day of
>>>operation with the fuel filler cap off before the DTC code is set and the
>>>check engine light comes on but...once it does come on your only option
>>>is to take the car to the dealer or get yourself an OBD2 code reader to
>>>reset it. If the dealer says you need expensive fuel system component
>>>repairs, get a second opinion as there may be absolutely nothing wrong.
>>>
>> There are a few other things that one can do to reset codes without
>> having a scanner. One is to go to a place like AutoZone who will read
>> the codes for you [ostensibly in the hopes that you will buy the part to
>> fix it] and then let you push the button to clear the codes.
>>
>> Another is to pull the fuse that resets the computer. A third is to
>> disconnect the battery for about a half hour [same as pulling the fuse as
>> far as the computer is concerned]. The second and third ways I have not
>> tried in a Prius, but they have worked in my Sienna. I would have to go
>> look up what fuse it is [something like the EMT fuse or something (???)],
>> but that is not happening right now.
>>
>> Hope this helps,
>> Tomes
>>
> Worth noting: most ECUs are learning devices. Killing the power to them,
> by pulling a fuse or disconnecting the battery, requires it to relearn
> everything it knew. That is not always a bad thing, though.
> Mike