2008 Justa (manual). I just replaced the spark plugs (over 100K miles probably original) and the thermostat housing. Thanks to a leaky valve cover gasket, the first plug (farthest to the passenger side) had a pool of oil in it. I got as much out as I could. I'm sure at most maybe a teaspoon of oil dripped into the cylinder when I pulled the old spark plug.

When I fired up the engine for the first time after the repairs the check engine light came on. I assumed it was the coolant temp sensor was in an air bubble and caused the error. I went to A***Z*** to ask them the turn off the cel. AZ claims their scan tool won't reset the cel. I had them scan the code anyway and it came up as an error with the cam position sensor. I replaced this sensor about a year ago. I find it too coincidental that it went bad just as I was doing this other work.

1) Is it possible that maybe the oil in the cylinder caused the error?
2) AZ suggested I just disconnect the battery to reset the cel...bad idea since it will reset everything?

 

I may have fixed the problem. I was just giving everything under the hood another look. One of the wiring connectors wasn't quite snapped together. It was on the driver's side at the top of the valve cover on the grill side. (above a 2-3 inch metal cylinder)

I would still appreciate opinions on disconnecting the battery to reset the cel or anything else if you think the connector isn't the issue.