I've had this truck for about 6 months now and recently started towing a trailer a couple of times each week A couple of weeks ago, the Check Engine indicator came on. It appeared when I started the engine with the trailer attached.
The next day I disconnected the battery just to see if it was a freak happening. A few days later I was parked on the EXACT same street location (doing lawn maintenance), started the engine and the light came on again.
Had it checked for a P071 code. So today I cleaned the MAF and pulled the EFI fuse which is one of the first things suggested. That may or may not solve the problem, but what I find strange is why does the light appear only when the trailer is attached? Could the trailer somehow be blocking exahaust flow and fooling the oxygen sensor? Two of the same occurances makes me wonder that there is something worth investigating.
ThreeWide