[Sly Bob]

Driving the car Friday I had the check engine light on and I call OnStar. They ran the diagnostics and tell me there is an issue with the high voltage battery and to get it to a dealer as soon as convenient. Took the car out a few times Saturday and the light is still on. Get in the car today and the check engine light is off. Have a hard time believing that the high voltage battery fixed itself.

I suspect that I'm not out of the woods, might take it to the dealer anyway.

 

[DonC]

Could be any number of things. Coolant. Pump. Loose connection. Even the battery pack, though that isn't likely. Lots of things. Definitely take it in.

 

[Steverino]

Errors can be reported when diagnostic values fall outside a given range x number of times. Maybe a sensor got some bad data, went flaky, was hit by cosmic rays?

 

[Cord]

So there IS an error code for "check engine light is on for no reason " ?

I am still looking for the code for check engine light is burned out but on.

Always good to get the code from onstar BEFORE it self clears as most auto places will not look for free if there is no engine light.

 

[BAZINGA]

If a code is generated and goes away it is still saved with an "H" for history appended to it so techs can see it and go from there. My 2014 Stingray threw a few codes that cleared (related to the emission guess the cap less fuel filler was acting up) and my ODBII code reader still displayed those codes even after the CEL went away.

Suggest taking it to your local dealer for their analysis.

 

[Norton]

Next time ask Onstar for the code number.
Could it be that you don't remember the description of the problem exactly?
Like 'High Voltage charging system'? That's a common one from a dip in the grid and goes away after a few complete charges.