For the past year I have been having this code pop up thus turning on the Check Engine light. Now I can't renew my registration until it is cleared. I took it to a mechanic nearby who does inspections and he spent most of the day working on it to no avail. Any suggestions?
Note: In the recent past I have had the following work/parts replaced:
fuel filter, fuel pump recall at Volvo dealership, O2 sensor(bank 1), air filter.
I recently removed the MAF sensor and air blowed out and am thinking of replacing ..after researching this problem.

Thanks,

 

Since you already changed the O2 sensor I would investigate a possible vacuum leak somewhere in the intake circuit. If no leak is found then a lot of chance the MAF sensor needs to be replaced.

 

Thanks for your reply. I went ahead and ordered the MAF sensor($130 @ RockAuto.com) but in the mean time I air cleaned the original one. Also, I found a badly cracked stiff plastic vacuum(?) hose going from the filtered air section to the engine and repaired. Finally I filled up with 93 octane. After resetting the check engine light, we'll drive for awhile and see what happens!