I learned the hard way that running the OBDII module, AFTER saving live data with the SCAN module, can/will automatically erase any recorded live scan data ... without warning!

I had performed extensive monitoring and saving of live data under the SCAN module during vehicle starting, warmup and then test drive ... leading to reproduction of a DTC being investigated.  I verified that the MD802 had actually recorded 4 DataStreams for viewing and transfer of data to a PC for more detailed analysis.

Unfortunately, as a last gesture, I used the OBDII module to probe further the DTC which had been produced by the above testing.  I then discovered to my horror, that some portions of the OBDII module had overwritten/replaced ALL the above recordings ... without any warning that it was about to do so.

THERE SHOULD BE A WARNING TO THE USER WHEN RECORDED DATA IS ABOUT TO BE DELETED BY A MENU SELCTION.  IT WOULD BE USEFUL TO HAVE THE OPTION OF ABORTING, DELETING, OR APPENDING THE NEW RECORDINGS TO EXISTING RECORDINGS!

This seems to happen because the live data recorded in the SCAN module saves to the SD, for this Toyota vehicle, in folder "/scan/MAKE/ASIA/TOYOTA/savedata".

Then the OBDII module saves MOST of its data (Freeze Frames) in folder "/scan/MAKE/EOBD/savedata"
... which does not affect the prior recordings.

However, SOME portions of the OBDII module also save their data (Data Streams), again, in folder "/scan/MAKE/ASIA/TOYOTA/savedata ... and automatically delete any existing Data Stream DATs ... and start again with new DATs.

PLEASE, Autel!  In a tool intended for professional or DIY users, provide some protection against accidental data erasure!  Make some mention in the user manual of this potential for data loss!

Thank you for listening!

Tags: MD802 , data_loss , warning , problem