You are welcome, either disconnect the battery negative terminal, then check everything or be very careful not to arc anything while live!

 

How far do I need to drive for the computer to relearn and decide if it still has a problem?

 

That sort of code should show real quick.

BUT; a couple weeks (at least 17 cold starts) for all of the other OBDII monitors to run. So don't disconnect the battery if you are needing an emissions test or safety inspection real soon after.

 

Turns out it was about 15 miles.

Code popped up again last night on the way home from work, and this morning the car started up, ran for about 30 seconds, and then quit. Had to take my 20-yr-old pickup to work instead. I feel completely ignorant about newer vehicles. Give me an old car and I can fix pretty much anything if I have a manual. This car, not so much.

 

There is a wire loose or shorted somewhere. First guess would be the ECM connector, second would be the harness near the exhaust pipe.

Or a shorted component.

Look for things that have been touched shortly before the CEL. Changed air filter, messed with the EVAP components, gotten near any of the wiring around the oil filter.

 

Thanks, that's a couple more things to try before I throw it at the mechanic$. Problem came out of the blue, I haven't been under the hood since changing the oil about 4 months ago, so nothing human has knocked anything loose lately. We have had incredible amounts of rain here in the last three months though, so it's conceivable maybe something has enough oxidation to not be making its connection, I suppose. I'll dig around some more.

I appreciate all the help, everyone!

 

I have no direct experience, generally speaking all "sensors" have a 5 volt reference. So, you need to check all of the engine sensors. There should be some other code pointing to the guilty one, but strange things happen in computer land.

 

Nope, there's no code other than P0641.