My SES light on my 2001 2500 Sub comes on and flashes when I exceed 70 mph or so. As soon as I slow to below 70 the light goes out. The truck seems to be running fine. I've had it to the dealer 3 times for this. The first time they changed the O2 sensor, the second time they told me the fuel rail needed to be cleaned and serviced and just last week they basically told me that it is not affecting "driveability" so I just just live with it. Anyone have and suggestions? I can just imagine that this might be a pre-cursor to some big failure in the future and can almost see the service manager salavating from here.

 

Have a local auto parts store hook up a scantool and retrieve any DTC's that are stored.

It could be a range of things from clogged or bad fuel injectors, EGR valve, etc.


There is a chance that it is a corroded ground terminal on the right side of the cylinder head at the front, this will cause a flashing SES with no drivability issues and it is very easy to check and fix should it be the cause.