Last weekend my check engine light went on in the early morning, ran around to most of the parts stores to find out that they will no longer to code readings on vehicles.

Was able to get a local garage to get me a code. P0101

Mass Air Flow

Engine compartment is extremely clean, no issues with wires, everything still in the same place when bought new as far as the harness goes.

Opened the air box, took out the air filter and dropped it on the side walk, one big cloud of dirt. Got a replacement filter. Went back home and took the air box apart, vacuumed it out, took the mass air flow unit off the box and cleaned that with Mass Air Flow cleaner by CRC. Put everything back together and then after a day of driving the check engine light went out and everything was okay.

Then last night the check engine light came back on.

Need to get the code read again.

What do you think could be the issue now?
Could it be the MAF unit?

Let me know. Thanks.

I have gone out and got a direct bosch replacement unit and put it in the car now. The check engine light still on and still reading the P0101 code. I have driven the car for two days with the replacement unit on at this point.

What else to do?

Don't know if this will do anything on a 2007, but it will work on older Volvos. Try leaving the battery disconnected for awhile. At least an hour, maybe overnight would be better? That would clear the computer and it will have to relearn.

From experience with other car brand having Bosch system: If cel comes back after doing the battery disconnect (can take 200 miles) you might have a problem with the long-term air/fuel mix reading. Can be an early sign of a lambda sond/oxygen sensor giving up, or a problem in electrical connections to same.

You might try driving the car for a week or more if it is running well.

When I had a new air mass sensor installed, the tech told me that the system probably adapted to the old one, and it might take several cycles to adapt to the new one.

Yup, it could take hundreds of miles for the computer to adapt. Try shutting off the check engine light if possible then drive it and see what happens...

Recently, my 2002 VW Passat had a check engine code for emissions. My mechanic shut off the check engine light (I really need to get a scanner for that car...:). Then I went to get the car inspected (emissions analysis is required in Mass for all cars 15 years old or newer). The inspection station couldn't do it. The inspector told me that with some cars it can take hundreds of miles for the computer to clear and readjust. After driving for a week or so I went back (check engine light did not return) and the car passed! Check engine light has NOT returned!

It could be an intake leak after the mass air flow sensor, a dirty throttle blade or a faulty mass air flow sensor.
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Keeping it running is better than buying new

Is there any easy way of servicing the throttle body on these cars? I have a power foam product that I would like to use on the throttle body, but since the throttle body is upside down on the intake manifold I don't have a clue as to how best to attack it.

Four 10 mm nuts, located in a perfect square pattern, hold the throttle body to the bottom of the intake manifold. You pretty much have to remove some air intake ducting to gain access. The biggest problem I have is getting the harness unplugged from the throttle body. Someday I'll master that one.
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Current rides: 2005 Volvo S80 2.5T, 2003 Volvo V70 2.4NA, 1973 Volvo 1800ES (getting ever closer to road worthiness)

On our '04 the wire is long enough to remove the throttle body with the harness attached. Once it is out where you can see it you can release the locking tabs.

Greg