Given you are getting IAT readings and there is a separate temp sensor, I'd say the diesels don't use a MAF based temp sensor. The qualifier is I've seem some ECMs sub a value that will show up on a scan tool but the actual sensor output is open / pegged.

An example is a coolant temp sensor on a Dodge mini van. If the wire breaks, voltage goes to 5 V ( -40* ) , if the engine is running for 5 minutes it can't possibly be at -40* so the computer subs a typical value for internal fuel calculation ( like 190 * F ) . If you read coolant temp on a scan tool it will show a believable 190 * , but if you call up the sensor voltage / read it with a meter it is 5 V / -40*

Had the same issue on a early 90's Mazda RX-7.

Also be aware that these MAF sensors have 2 sources of power going into them. One is 12 V to power the sensor, the other is a 5V reference from the ECU. This 5 V ref is altered to give an air flow reading out.

The p0100 still tells us nothing beyond it is related to the MAF system, we need a MB specific description. Very specific descriptions of trouble codes make an accurate diagnosis possible, anything else results in random parts replacement.