On 2018-07-02 20:35, ken wrote:
On 07/02/2018 06:37 AM, jdd@dodin.org wrote:
Le 02/07/2018 à 12:32, ken a écrit :
scanners".) One tip I'd pass along, before buying, check the operating temperature range. One of the "scanners" I bought died in the first year
they a most of time time sold to fix engine problems, not to be there all along :-(
jdd
Some vehicle problems, perhaps most, first appear intermittently. The logic in an ECU, however, will routinely erase what it sees as a one-off error and not report it via "Check Engine" or with a code reader until it recurs multiple times within a specified amount of time. I was once able to anticipate a problem, long before the ECU's logic deemed it a problem, because my home-brew system provided me longer term raw data, which was much more informative.
In addition, a problem may appear only within a particular constellation of other varying conditions; just reading the lone problem code will not reveal those other relevant conditions, conditions which may well normally vary over time... or perhaps should not vary significantly. E.g., ask most any auto mechanic, quite often an error code points to some part which is not the problem at all; instead the "problem" is the fault of the reporting sensor, something which can't be determined simply by reading one, single code after the fact, but is obvious in the context of other data.
Happened to me. An alarm popped up "take the car to the garage". They replaced something, charged me something, I went away, and after some days I was back with the same alarm. The mechanic only found out what was wrong after driving for a while with his laptop connected to the car for some time and scanning the logs. Intermittent failure in a different sensor that what the initial report said. -- Cheers / Saludos, Carlos E. R. (from 42.3 x86_64 "Malachite" at Telcontar)