So I had noticed recently that my 2006 WRX was idling a little rough when it first started up and every couple of seconds little white puffs of smoke would come out of the exhaust. I decided to try using Seafoam for in the gas tank and BPV vacuum line. After reading multiple posts, I decided not to put it in the crankcase. Adding to the gas tank was easy (long-neck funnel). I disconnected the hose from the BPV and slowly poured 1/3 of the Seafoam into it and it sputtered a lot as I expected. I read in multiple posts that you are supposed to pour a good dose in at the end to stall the car. I let it set for about 15 minutes and started her up. A good amount of white smoke came out. The car seemed to idle a lot better and run smoother.
After driving it around for about 5 miles the CEL came on and the Cruise Control light started flashing. The Cruise Control also wasn't working. The car was running fine but I immediately drove back home and shut it off. I started it up again and the CEL and Cruise Control were still on. I disconnected the battery to reset the ECU and the CEL and Cruise Control went away and the car drove fine. My question is...did I do permanent damage by stalling out the car? After the issues arose I did some research online and read in a few places that you can damage your O2 sensors and spark plugs by dumping too much Seafoam in at once and intentionally stalling the car.