My check engine light came on. Scanned the system and found code P2271. I took my truck to the dealer and they confirmed the code. They told me that the oxygen sensor was shorted internally. They replaced both sensors and installed a new sensor overlay harness at a cost to me of $1481.68. My warranty expired 2 days before my check engine light came on and they would not cover this under warranty. A couple years before this, when my truck was under warranty my check engine light came on, I took it to the same dealer and they told me it was my oxygen sensor. They replaced it under warranty? From what I have researched on the internet, this is a common problem, the wire gauge used in the wire harness to the O2 sensor is to small.