My engine has a burning smell when driving on the Interstate. It is not leaking oil or any other fluid. The Toyota technician thinks it might be coming from the catalytic converter. How serious is this problem?
Not extremely, although you do want to address the issue, and it may very well be the Cat. However, smell the dipsticks of the oil and the transmission fluid, also take a look at the the dipsticks to see if there are any foreign objects such as metal shavings, if any foreign items are present, obviously you will need a trained mechanic to look further.