Any time the HFM sensor voltage exceeds 1.03v with engine not running, the sensor is faulty. 1.07V is usually the voltage these read when code PO170 and 173 are present.
I would also recommend replacement at this time.
Make sure the air filter is not leaking or pinched around the seal.
check all seals, pipes, and clamps. Dirt is a airmass sensor's
worst enemy.
The codes can be pulled with a universal obd2 scan tool.
the codes will need to be cleared and self adaptation reset
after the sensor replacement.
I would have a MB shop do this.
Good luck.
DR.D