We have gone through one of those dark periods where it seems like our '06 Escape was requiring deep investment to stay rolling. Once we had almost everything resolved, the Check Engine light popped on, and the Service Emission System message appeared, and would not clear. We had the feeling so many mechanics had touched the car, this could just be an oversight.
I dropped by AutoZone, they ran the codes for me, (070, 071) and they told me most likely, I needed a new Mass Air Flow Sensor. I bought one for $95 and replaced it, but the message stayed on. I did some more research, and found out I could have just bought a $9 can of aerosol cleaner and used the old part. I tried that, but the Check Engine light/message still stayed on. Put the new part back, saved the old part.
Two days later, we drove the car to Vancouver and back, without any loss of power, or fuel economy. According to the forums, if that message was correct, we would have been stuck in "Limp Home" (2nd gear ) mode. The only nuance we noticed, at the border crossing it refused to kick into battery mode, so we could glide in the polluted gridlock.
I took the car to our Ford garage, they wanted me to leave the car for two days and estimated $560 to diagnose and repair. I asked them if that code needed to be reset. They gave me a blank stare. I did not drop off the car, but kept driving with the check engine light glowing.
I was about to take another stab, but got busy, and actually ran the gas tank to almost empty, prompting the LOW FUEL message to pop on, and I noticed the Check Engine light was off! Once I filled the tank, the check engine light stayed off, and the message was back to the standard, number of miles until empty. And the electric mode once more works at traffic lights and pulling into the garage at night, same as it ever was.
Just passing this along. Love the Forums for educating guys like me, who used to just pester busy mechanics.