Codes showed up after oil change

I recently took my car in for an oil change, the plug was stripped so my local oil change place advised me to take it to the dealership to get it done as they would have a replacement on hand. Immediately after the oil change I had several waning lights show up. The first was my traction control and PCS lights then my service engine soon and then my ABS. I took it back to the dealership and they scanned it, for a fee of course. They said it had nothing to do with them, of course, and advised me of the following codes, P1122, P1189, P1811, U1153, C0035. I have also had issues with the signals working intermittently. They did not actually look at anything but the diagnostic, yet they "are very concerned" about P1811 & C0035 and gave me a guesstimate of about $1200 to fix it. I have noticed no difference in driving or handling of the vehicle. Is it possible that the codes are inaccurate? Thoughts or opinions please.