We have a 2010 RRS that is barely two months old. A couple weeks ago the CEL came on so I brought it in to the dealer. This is what they wrote on the invoice: "852 oil filler cap not fully seated Ran SDD found P2099-00 bank 2 fuel trim too rich. Ran data logger and monitored oxygen sensors. Found sensors are moving accordingly when removing oil filler cap. Found cap was not tightened down. Reinstalled oil filler cap correctly. Cleared faults and PCM adaptions." No charge, but as they were pulling the car up for me, the CEL light came on again. So I requested they fix it again, and drove the loaner XF home. I ended up in the XF for 3 nights, missing the RRS the entire time. Finally got it back less than a week ago. This time, this is what they wrote on the invoice: "875 Found bank 2 (drivers side) downstream oxygen sensor has failed. Ran SDD found P2099-00. Fault returns with every drive sets light on second drive cycle. Contacted tech line. Advised to check fuel adaptions, swap rear oxygen sensors, reset adaptions, clear faults and test drive. Found unable to swap sensors due to different length pig tail harness on other sensor. Had to clear adaptions 3 times SDD failed on all other tries. Could not save fuel adaptions file view. SDD had a general fault. Swapped in a rear o2 sensor from another vehicle on the lot. Cleared adaptions from legacy IDS and cleared faults. Fault did not return after oxygen sensor replacement. Removed sensor and installed new sensor. Installed old sensor back into stock unit. Test drove and fault does not return. Check ok after repair."
This morning the CEL is back. Any ideas guys? The car was at 850 miles when the first CEL came on, 855 when it came on a second time, and is at about 1100 miles now. It was a May 2010 build. Ohio is a lemon law state I believe, so they get one more chance to get it right before it's officially a lemon. I don't want another car or a repurchase or a refund, I just want the problem to go away.