On my 2001 V70 Wagon, we are thinking it is the MAF sensor or fuel trims (running rich or lean). When I took it to my mechanic today, the check engine light was not on, it ran great getting there and he told me he can't diagnose without a check engine light on. He did clean the MAF about a year ago. Perhaps I need a new one. This very same thing happened with my 2003 S60 Turbo so I knew to ask him about the MAF, but we are a bit stymied. Then later in the day after I left the mechanic, check engine light came on it was sputtering like it wanted to stall. Any suggestions?

 

Check engine light means a code is stored - what code? Or are there are pending codes, things that could produce a check engine light but have not occurred enough times yet (for instance a missfire, a few times is ok, but too many turns the light on)