Bought a used 2007 tc. After driving it for 2 weeks I pulled out a spark plug to see what they looked like. It looked pretty old. Car had 94K at the time. Next morning I had a check engine light. Changed oil, filter, plugs, air filter. Still have check engine light and car is throwing multiple codes, P0138, P0441, P0455, P0606. Car runs great no issues at all. Just a pesky check engine light. Any thoughts out there. Didn't have a problem til I pulled out a spark plug.

 

http://www.obd-codes.com/p0606

http://www.obd-codes.com/p0455

http://www.obd-codes.com/p0441

http://www.obd-codes.com/p0138

 

Perhaps you knocked a vacuum line off or broke one while servicing.

 

Vacuum line was the first thing I checked. Maye it's just coinsidence but after looking at the explanation of the codes, I notice the gas cap comes loose really easy. Practically falls off when removing. Could a bad gas cap cause that many codes? Also are iridium plugs a must? The ones I got weren't iridium.