I read a lot about these ECU error codes. Where do you read these codes? I have heard that you read the flashes on computer located in the passenger footwell. It seems a lot of hassle, is this true?

Do people just regularly check the computer just to see if there are any problems as part of routine maintenance?

I am just curious because I read a lot about people saying "I have been recently getting error codes indicating.....etc" It seems to me that these error codes are displayed conveniently on the dash or something.