I have msAccess clients running smoothly with MySQL backend via ODBC.

When I test the execution of various invalid sql statements the only error received is 3146 'ODBC--call failed’.

Is it possible to query MySQL to discover more detail regarding the last error and return a more meaningful message?

yes, it is

test your queries with a front end tool like phpmyadmin or mysql-front or sqlyog or any of a dozen similar ones, some of them even free

How do I extract error-codes and error-mesages AFTER a failed query.

(not how to create queries that don't fail)

i think that would be an odbc question, not a mysql question

and meanwhile, testing your queries where you can see the error messages is still advised