I have not checked. I have an extra ecu as backup, I replaced the current one 6 months ago when it went bad, that's when I had the fuel pump and igniter replaced. When I picked it up at the shop the check engine light came on for a few seconds and then disappeared. Mechanic disconnected battery and then reconnected saying this would "fix" the check engine light problem. Monty has not faltered once in the past 6 months while logging close to 5k miles. The light comes on maybe twice a week, like I mentioned, for 6-10 seconds, then goes off. I was thinking it had to do with the exhaust, one of the sensors or something....should I replace my ecu with the other unit then, and is it just a plug n play ?