1999 Ford MustangDecember 18, 2015December 18, 2015 check engine light on:1999 Ford Mustang,3.8L. 6 cylinder. Keywords:mustang 1 thought on “1999 Ford Mustang” FreeAutoMechanic December 18, 2015 at 10:36 am If the light is on and not flashing, it is generally an emissions related issue and may be dealt with when ever you have time. However if the check engine light is flashing, do not drive it and take it to the shop ASAP. Permanent damage may occur if you continue to drive with the light flashing. A Scan tool is required to pull the check engine light trouble codes. Just about any local auto parts dealer will perform this task for free. Once you have the codes, post them below and we can dig further into your issue. Comments are closed.