yes and no.. your check engine light will still come on as its only a light on the dash. same with the abs/brake light and oil light. you will lose, however, the readout specifying what the problem is - i.e. your check engine light may come on ... but you'll have no idea why. if you had the LCD it would say (for instance) emissions workshop or service in xxxx miles. without the LCD it will just trip the check engine light and you wont know why.